Any tank you ever set up will be subject to an algae outbreak sometime. The trick is to learn to manage, rather than completely eradicate it.
WORDS: NATHAN HILL
Every newcomer to the hobby will be united in asking, somewhere around three or four weeks into their experience, about how to deal with the algae forming in their tanks.
It’s no coincidence that some tanks are hit harder with the green stuff than others. Algae are numerous in their forms, from microscopic green ‘orbs’ that drift like balloons, to long, pernicious strands of red or black that carry the resilience of a born survivor.
The basic algae problem involves a tank full of water, light (which supports plant life), nutrients (either too much or too little) and carbon dioxide (which may or may not be in your control.) Wherever these ingredients are found, they present an opportunity for algae to grow.
For the everyday aquarist, there are a few strains that might appear, and there are different ways to deal with each one. Algae is not algae, is not algae. There are the green
and red varieties, needing different handling approaches, plus the peril of ‘algae’ that isn’t even true algae.
It’s important to diagnose and understand what type you’re up against before you decide on what action to take against it.
This is quite a rarity in tanks (as opposed to ponds) unless you’re tampering with carbon dioxide and nutrient levels, but it can still strike out of the blue.
The cause is a unicellular alga that lives free in the water, too small to get trapped in filters, and too persistent to be diluted out with a simple water change or two.
Ammonia is implicated in causing and sustaining green water, and stirring up substrates, subsequently releasing ammonia in to the water, can be a trigger. Off the shelf algaecides may help, water changes do very little, and my own experiences have found that a temporary black out where lights are turned off and the tank shrouded to keep out any external light will help reduce it, but not always eradicate it.
To add to the frustration, it will often disappear in a day or two entirely on its own.
Green dust algae
An alga type that’s found mainly in new set-ups, green dust lives up to its name. It mainly forms on the glass and hard, smooth decoration like rounded stones, and
given time to cement itself in place it can be stubborn.
Attacking it frequently seems to make it linger, and aquascapers will sometimes just leave it alone for several weeks (until the glass becomes near impossible to see through) before removing en-masse by scraping it from the glass with a blade or plastic edged cleaner, and then syphoning out the removed algae from the base.
Oddly, in heavily planted tanks, a low level of nutrients can be part of the cause, but unless you’re a dedicated aquascaper you won’t want to add more plant food!
Blue green algae/cyano
If you suffer from this, then I feel for you. Blue green algae isn’t algae in the true sense, but is a type of bacteria that can photosynthesise. It will quickly drape all that it can in a tank with thin, expansive sheets that often peel away in large pieces. Controlling it is nightmarish, and short of using antibiotics (which are illegal without prescription in the UK) you’ve a long fight on your hands.
In a home tank, the cause is usually a combination of direct sunlight hitting the glass, combined with dirty substrates that harbour rich beds of organic matter. Ammonia can trigger it, and a new tank is likelier to get it than an old one.
To start controlling it, you need to physically remove as much as you can via net and syphon. At the same time, you need to work on substrates to get them scrupulously clean, as any muck down there will entice it to return.
To eradicate it, you’ll need a complete tank blackout for around four days, so turn off all lights and wrap the tank in something dark so that light can’t get in. It’s noted that increasing oxygen levels can also help out, so get an airstone in the tank too.
This is the most common alga you’ll meet, and it’s formed of tiny diatoms. If you’ve set up a new tank, it’s the first alga that will appear, and is associated almost entirely with the silicates and ammonia that goes hand in hand with an unestablished system.
Brown algae will vanish within a few weeks of setting up. If it doesn’t, that algae isn’t the problem, but rather something is stifling the maturing process of the tank. It may be an issue with the filter, or it may even be excess movement of the substrate. Stirring the base up too often can cause it to linger, but only when the tank is new.
Dealing with it is as easy as getting in the tank with an algae pad, wiping it from the glass or other hard surfaces, and then syphoning out what drops to the base of
Though some fish (like Otocinclus) will eat it, the paradox is that brown algae will almost always indicate a tank too immature to keep them. Clean and wait, and eventually the algae will go.
Green spot algae
Not to be confused with green dust algae, green spot is more tenacious and stubborn, with larger individual blobs.
In aquascapes, it tends to be associated with low CO2 and low nutrient levels, where in most domestic community tanks it tends to be a consequence of excessive lighting and poor water flow. Bright, near-static tanks are almost always problematic.
To clean from glass, hard scrubbing with a pad or magnetic cleaner will keep it in check, though a razor or plastic edge may be needed to remove it once it gets a foothold.
Green spot algae on decoration will require scrubbing with a toothbrush. Remove affected decor and brush it under running water.
Leaves showing coverage of spots are best removed using sharp scissors.
Performing a series of small water changes (10% daily for five days) may help to reduce some of the available nutrients. Cut back on the amount of light during the day — anything over eight hours is inviting green spot.
Black brush algae
‘Black’ algae is misleading, as this is actually classed as red algae. In the tank, it tends to be more of a sooty grey, but its presence is unmistakeable. Small, beardlike tufts of dark, fluffy algae will jut from all surfaces, ornaments and plants in a slow encroachment, until eventually the whole tank is smothered.
It’s associated with a few factors in community tanks. High phosphates are implicated, as is inadequate flow of water. Old light tubes in particular seem to promote its growth, and fluorescents over 12 months of age should be replaced to prevent it.
It can often be found living directly on wood, feeding on leeching organics.
Controlling it is nightmarish. Any plants that show signs of infestation should have the affected leaves sacrificed immediately. Any growths on glass should be scraped away with blades or plastic edges, and the tank syphoned to removed the fragments immediately after.
Decor that is smothered can be treated by removing it from the tank and soaking it for five minutes in a mixture of glutaraldehyde (such as Easycarbo, or Flourish excel) at a ratio of 25% treatment to 75% water. After soaking, rinse thoroughly before returning to the tank. Dosing Easycarbo to the tank will help to control brush algae in the long term, as it’s toxic to the algae but not to higher plants.
Water changes will help in some cases, while less water changing helps in others, as will certain fish and shrimps. Try redirecting filter outlets to provide more flow around the tank, or even consider an additional small pump or powerhead to increase movement.
Looking similar to black brush algae when small, staghorn forms long, antler-like tangles. It tends to prefer plants over substrates or decor, smothering leaves with its growth.
Dirty tanks with sediment trapped in the substrate are desired real estate for staghorn, and toss in slow water flow and ageing lights, and you’ve a perfect recipe for growth.
Cleaning the substrate, removing affected leaves, and treating with glutaraldehyde will all help, as will improved flow rates.
Fish and inverts: Some fish will consume algae as part of their natural diet. In fact, many species have long been marketed as remedies to outbreaks. Here are some of the classics...
WHY NOT TRY THESE ARTICLES...
Increasing numbers of fishkeepers are adding sumps to their set-ups. We answer some of your common questions.
How do I ensure my sump doesn’t flood in a power cut?
There are two ways to prevent flooding.
One involves placing the outlet of the pump high up in the main tank, close to the surface. When the power fails the pump will back syphon slightly, but, as soon as the outlet pipe is exposed to the air, the flow will stop.
The second is a popular method if you want the outlet positioned lower down in the main tank.
The easiest way to stop back syphoning is to make the outlet pipe draw in air and break the syphon. If the pipe is low down in the water, drill a 5-6 mm/ 1/4” hole in the pipe near the surface, so again, as soon as the extra hole is exposed, air is drawn in and the syphon broken.
If you don’t want to drill your own holes, use a spray bar return either horizontally, just beneath the water line, or vertically, so that as soon as the first spray bar hole is exposed the same action occurs.
Always ensure there is more than enough empty space in your sump to deal with rapid floods.
What size of sump do I need for my tank?
The bigger the better as it will increase water volume and stability of parameters. But many sumps are dictated by the size of the cabinet.
However, the minimum-sized sump must still be able to hold additional water from pipework and surface area of the main tank when the power goes off. Leaving a gap above all your media and refugium can allow for this extra water. Most ready-made sumps are designed this way.
Ensure that if you illuminate the sump, the lighting is not flooded in such situations.
How can I reduce the noise in my weir?
Too much flow down an outlet or standpipe creates the noisy, sink plughole effect – and the greater the flow the noisier it gets.
Standpipe noise can be sorted at the design stage. Anything more than 2000 lph/ 435 gal down a 25 mm/0.9” diameter standpipe can sound noisy.
If you want even greater flow, as many 300 l/66 gal-plus marine tanks do, use two standpipes, either together or one in each corner behind two weirs.
You can also counteract the bottle 'glugging' effect in standpipes, where water flows down the pipe but air wants to escape up it. As a result the pipe floods slightly before the weight of the water gushes down and the air whooshes back up, making that loud glugging noise.
To counteract this, fit a rigid 'T' piece at the top of the standpipe and ensure it is exposed to the air above the water line. The horizontal part of the 'T' is where the tank water will enter and the vertical part is left free for air to enter. More water can then flow down the pipe, producing less noise.
Fill weirs without standpipes with plastic media to stop splashing noises.
I’ve been told that my total turnover should be 20 times per hour. Does this water have to circulate through my sump?
In a word, no, and as discussed above, more than a few thousand litres per hour down standard 25 mm/0.9” standpipes can make noise and cause flooding.
When 20 times turnover is recommended, it means by powerheads in the main tank, not by sump pumps. It would be nice to pull water through the sump that often but the reality is that the sump turns into a whirling, splashing, noisy extra tank, unless it is more than 120 cm/48" long.
If you intend to have a refugium in the tank, the manufacturer may well include flow recommendations.
Is there any benefit in using sumps on freshwater systems?
There will always be a place for sumps on very large freshwater tanks, but most tanks – even up to 240 x 60 x 60 cm/94” x 24” x 24” – can be run with a lot less fuss on a couple of large external filters.
Saltwater sumps are more necessary for marine tanks, if not purely to serve as somewhere else to put the equipment. A marine sump can serve a skimmer, calcium reactor, heater, chiller, chemical media, other filter media, automatic top up, water change water, a refugium, a drain, and much more. It can also be used to hold fish and raise young marine fish.
Lessons can be learned from marine sumps and planted refugiums could well be the way forward for future freshwater tanks.
How should I design my sump?
This should be done during early system design to be compatible with your method of filtration.
Will it hold mechanical, biological media and a heater? If so, the standard up and over design with glass baffles will be fine.
Divide the sump into sections with water entering at one end and exiting at the other – but in the middle being forced up and down through the baffles and through media. If adding a sump-based skimmer, leave an extra chamber after the mechanical media.
A deep sand bed or a mud refugium in the sump will need a section, normally at least 30 x 30 cm/12” x 12”, to hold the sand or mud. In these designs the water isn’t pushed down through the sand or mud but flows over it. Water should enter and exit the bed at least 10 cm/4” off the bottom so that the sand/mud won’t get washed away, and because sand beds need to be 10 cm/4” deep to function properly.
If growing Caulerpa over the mud or sand, it must have plastic media either side to prevent it travelling through the sump and clogging the return pipe. The sump also needs to be lit.
Any advice on for how long Caulerpa should be illuminated in a refugium?
Some people light the algae for 10–12 hours each day on a reverse cycle to that in the main display tank. This way the pH swing is counteracted as the algaes in the main tank produce CO2 at night and the algae in the sump uses it up and buffers night time pH values by producing oxygen.
The reverse lighting method makes sense and is used effectively by some, but the algae can still crash as easily as if in the main tank. If you light macro algae 24/7 it is less likely to crash and the population will be more stable and much easier to control.
What weir design is for me?
Make water exit through a hole drilled in the back or base of the tank. Back holes are more prone to flooding and wrongly sited may affect where your water line is in relation to the hood.
Base holes make for easier water level adjustment by adjusting the length of the standpipe, though they normally have a glass or acrylic weir in front. Water floods over the top, draining to the sump. Weirs are always fractionally shorter than the tank rim so water goes over them first.
Do you want water to be drawn from the top of the tank, bottom – or both?
A top-scavenging weir can be simply glued in and water floods over the top, but add an acrylic comb or slots to prevent fish flowing in. This type of weir is really good for clearing scum off the surface.
A bottom-scavenging weir involves fitting an extra plate in front of the glass weir, with slots in the bottom. This breaks the water line, forcing floodwater to exit through slots at the bottom before travelling up and over the normal glass weir behind. Bottom scavenging weirs are good for removing detritus from the bottom of the tank.
A weir can scavenge both top and bottom so fit an acrylic plate in front of the glass one and make slots in the top and bottom. That way you get the best of both worlds. If you are a little confused, specialist tank manufacturers will know what you mean when you mention weirs.
Want to know more about ULNS? Eric Michael Sanchez has some answers that may help.
What constitutes “ultra low nutrient” and what makes an Ultra Low Nutrient System?
It’s a reef aquarium that maintains very low levels of nutrients. The word 'nutrient' itself is a broad term, but the levels we focus on are nitrate (NO3) and phosphate (PO4).
In an ultra low nutrient environment these should be undetectable on hobbyist grade test kits. For high sensitivity testing, nitrate levels between 0-1ppm and phosphate levels of less than 0.03ppm are generally considered low, or ultra low, nutrient.
Even at these seemingly low levels, when compared to the ocean’s stony reefs we attempt to mimic they are extremely elevated.
An ultra low nutrient environment can be created in many ways. However, the term ultra low nutrient system (ULNS) is most often associated with probiotic or bacteria-driven systems due to their efficiency in reducing nitrate and phosphate levels.
What’s the point and what are the benefits?
Low nutrients are paramount for the avid SPS or Acropora aficionado. Reef aquariums exhibit elevated nutrient levels compared to the oligotrophic (nutrient poor) waters where the SPS corals naturally occur.
Under elevated levels of nutrients, such as phosphate, stony corals exhibit suppressed calcification — reduced growth. This issue can be eliminated in aquariums thanks to modern filtration technology, but colour is another benefit as a result of low nutrients.
SPS corals gain energy from zooxanthellae, their symbiotic algae that is generally gold/brown and can be seen through the coral’s flesh. As nitrogen permeates the coral tissue, the zooxanthellae underneath can quickly utilise it to grow. Elevated nutrients fertilise the zooxanthellae and cause dense levels within the coral tissue, resulting in drab brown corals.
When these nutrient levels are decreased so are the zooxanthellae densities. This allows more coral pigmentation to be shown and less of the colour brown.
With such low levels of nitrogen and phosphate, algal growth can also be significantly reduced.
There is also evidence that bacteria in the water column can serve as a food source for corals. This has prompted some aquarists to incorporate ULNS techniques to help manage nutrient levels while providing that food.
How can my aquarium become ultra low nutrient?
How nutrient levels are reduced and maintained is up to the aquarist, but bacteria driven, ultra- low nutrient systems based on organic carbon dosing have quickly become popular.
Organic carbon is added to the aquarium in stringent low doses to cultivate bacteria in the water and, in some cases, within reactors. This is not without risk but, if done properly, the end result is a powerful nutrient reduction.
Many proprietary systems are based around the idea of organic carbon such as ZEOvit, UltraLith and Prodibio, but even sugar and vodka additions follow the same underlying principles.
How do bacteria lower nutrients?
As the bacteria reproduce from the addition of carbon, other inputs are then required for synthesis, namely nitrogen and phosphate. The bacteria can then assimilate nitrate and phosphate in the aquarium, incorporating it into the growing biomass which is then removed via protein skimming.
The skimmers are vital for exporting the bacteria and utilised nutrients. High levels of nitrate and phosphate have become undetectable after weeks or, in some cases, even days.
This is the basic premise of commercial bacteria-based filtration methods, as well as vodka and mixed carbon source dosing such as VSV (vodka-sugar-vinegar).
Will water chemistry be affected?
ULNS can magnify issues from parameter shifts. Under traditional filtration methods changes in parameters can cause stunted growth or browning. Mortality is not uncommon.
Fluctuations and shifts in alkalinity can cause harmful coral tissue necrosis. The link between bacteria-driven systems, alkalinity, and coral mortality is still not fully understood. However, with some good husbandry and testing practices, this can largely be avoided.
Ideal ULNS parameters are alkalinity 7-8 KH, 400-450ppm calcium and 1,250-1,350ppm magnesium.
What about commercial products?
Some products rely on organic carbon and bacteria. Few companies release the ingredients of their products, making it difficult to assess and compare these systems. That said, most of these incorporate organic carbon source, bacteria strain supplement, amino acids and trace elements.
Arguably the most controversial additives included in these proprietary ULNS systems are amino acids and trace elements. The bacteria and corals can utilise both, but do we really need them?
Testing of total nitrogen and various trace elements is not only difficult but cost prohibitive.
Anecdotal evidence suggests some validity for both. For example, only in these bacteria-driven systems are we seeing concerns with potassium levels.
Interestingly, potassium is utilised by many bacteria strains for the correct functioning of enzymes and other processes. Amino acid solutions have been noted to darken Acropora coloration, suggesting nitrogen limitation may be a concern.
No matter what product line or DIY method is chosen, each aquarium will be unique in its bacteria, carbon, nitrogen, and phosphate profiles. Product guidelines are just that and must be fine-tuned by the aquarist for optimum performance. This can be difficult and is why such systems are not advised for the beginner.
Why are zeolites sometimes used?
Zeolites act as a molecular sieve to attract compounds or elements. They are well known for ammonia removal in freshwater and these are utilised in a similar fashion for ULNS. Most zeolites marketed for freshwater also have an affinity for calcium and are not suitable for saltwater — so be careful when making your choice.
There are more than 100 types of zeolites. Manufacturers rarely state types used, but market them as ammonia binding. The extent of ammonia adsorption is likely much less in an ionic solution (saltwater) than in a non-ionic solution (freshwater). However, it is assumed that absorbed ammonia creates a nutrient-rich layer on the zeolites that provide an ideal substrate for the bacteria to colonise.
Without knowing the specific zeolites used it is difficult to determine the water chemistry impact they have in saltwater. No independent research has been done so far.
Why are some corals in ULNS pastel in colour?
Near bleached pastel coloration of corals is often identified with ULNS. Low nutrient levels do lend themselves to these soft, bright colours, but this is often taken a step further with trace elements with known toxicity to zooxanthellae.
Low levels of copper and zinc can cause corals to expel zooxanthellae. These elements are included in some popular colour manipulating additives as well as variations of the balling method.
The inclusion of such additives is a matter of choice. They are not required for these methods to be successful and ULNS can be utilised without pastel corals.
Is ULNS for me?
ULNS is intended to replicate the nutrient poor conditions found on shallow water coral reefs. If applied properly, it can result in thriving corals while reducing nuisance algae. However, these systems are powerful, costly, and, if misused, can cause complications.
These methods are gaining acceptance, but ULNS is not for everyone. It calls for strict discipline on the part of advanced reefkeepers.
Want to see some great ULNS reef tanks?
This article was first published in the June 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.
Parrot cichlids are controversial fish. Matt Clarke takes an open-minded look at them and answers some of the most common questions.
What is their scientific name?
Parrot cichlids don't have a scientific name, as such, as they're not a real species. These fish are a hybrid (a cross between species) first produced by fish suppliers in Taiwan in the late 1980s. The names of hybrids are usually written as the scientific name of each parent separated by an "x". A cross between a goldfish and a carp, for example, would be Carassius auratus x Cyprinus carpio.
What fish were crossed to produce this hybrid?
Nobody knows for sure, but the parent species were definitely Central American cichlids. Various combinations have been suggested from straight crosses between red cichlids such as the Red devil or Midas cichlid with Convicts, Severum or Quetzal cichlids, but it's also possible that these may have been produced by crossing more than two fish together.
It is possible to cross a Severum with a Convict to produce a hybrid fish and then to cross that hybrid with a Red devil, to produce something with a mixture of genes from the three others in its genome. The first Parrots were probably mutants in a batch of fry and may have been selected from to produce the current strains.
Hybridising cichlids is something enthusiasts vehemently protest against. It is not a good idea to try this at home. You can't produce a new species in this way. New species aren't formed by two others crossing together, they usually evolve over thousands or millions of years. Hybrids are largely considered worthless and unsaleable, but the comical appearance of these fish, and some clever marketing, has made these a popular fish with some fishkeepers.
So if I cross my Red devil with my Synspilum the fry will be Parrot cichlids?
That's extremely unlikely. The fry will probably be fairly nondescript hybrids with some of the features of each parent. They almost certainly won't have the parrot-like body shape. This is likely to have been a mutation that cropped up. The mutant fish will have been bred from and their offspring may have eventually been fixed to produce parrot offspring.
Hybrid cichlids are essentially unsaleable. Clever marketing by dealers in the Far East did create a demand for so-called Flowerhorn cichlids (which is essentially what you've created are) but that demand is now a thing of the past. Hybrids have no value, so don't try to cross your fish.
So what is "the" Parrot cichlid?
The "real" Parrot cichlid is a large silvery-green species from the Amazon basin called Hoplarchus psittacus. However, the chances of you buying one of these, or even seeing one for sale, are about as likely as me receiving my annual bonus; pretty slim but not completely implausible. The real Parrot cichlid is pretty rare in the shops (I've only seen a few of them for sale) and you're not going to get the two confused.
Why can't my Parrot shut its mouth?
This is normal among Parrot cichlids. The mouth is deformed to produce the beak-like appearance which gives these fish their common name. Some people believe that the fish are unable to feed, which is not the case. How else would breeders grow them on to a salable size?
Cichlids have a special piece of dental apparatus known as the "pharyngeal mill" in the back of the mouth which allows them to mash up food and eat it. This does not appear to cause them too many problems in the long term.
So why are their heads deformed?
This is most probably a mutation which has been selected-for by the breeder. Some Internet sources have claimed that the shape is produced when rubber bands are tied around the head of the young fish. In a recent paper on man-made fishes, OFI President Svein Fossa said:
"It seems to strange to be true, but I cannot offer evidence to the contrary. The people in the markets that are faced with accusations of what many people regard as cruelty to animals cannot provide evidence against this."
I am told they have deformed swimbladders?
This is quite feasible. X-rays of fancy goldfish with a similar body shape have shown that the swimbladder and other organs are essentially squashed into a smaller cavity. So, you could say this "deforms" the swimbladder, though all of the innards are soft, anyway. This does cause problems in fancy goldfish where swimbladder disorders are rife, however, I haven't heard much of this among Parrot cichlids, though it is theoretically quite possible.
Why do some people hate these fish?
Many fishkeepers are against hybridising fish to produce new ones, and many dislike the way that deformities have been positively selected for in the Parrot cichlid. The fish are quite far-removed from their parent species and rather deformed. They're sometimes dyed too, and some may also be unable to reproduce.
If many people hate these fish, why do shops still stock them?
Shops stock them because people buy them. Retailers want to make money and many of them don't see Parrots as bad enough not to sell. On the other hand, many stores won't stock these, and we run a campaign asking retailers not to stock any that have been dyed. This is, sadly, something that is quite common with Parrot cichlids. We'd certainly advise you to avoid these dyed ones, and the shops that choose to sell them.
Is PFK anti-parrot cichlid?
We're not against parrots per se. However, it is no secret that most of our writers think that these fish are monstrosities, and all of them have very strong views about hybrids and dyeing. There are literally thousands of beautiful natural species on sale and we'd much rather you kept these instead. They'll also breed, too. But, if you do want to keep Parrots, then it's our job to give you the facts you need to make sure they're well looked after.
Are they sterile?
Some have said they are, but I don't believe they are in every case. Parrots often spawn in the aquarium but they don't always produce viable offspring (unlike many other hybrid cichlids, which can breed as readily as the parents). However, quite a few people have reported successful spawnings with some varieties of Parrot cichlid.
How big do they grow?
Given enough space you should be able to get your Parrots up to 15cm/6", sometimes a little more.
How do I replicate their biotope?
Since these aren't found in the wild, it's not possible to create a tank which represents their natural habitat: they don't have one. However, the species which they are probably descended from usually live among rocks on the margins of Central American lakes and rivers.
What sort of water conditions do they need?
The parent species are almost certainly of Central American origin, so they will have probably evolved to live in alkaline water. Unadjusted, hard alkaline water is fine for these fish and they are unfussy and easy to keep in the aquarium.
Are they OK in a community tank?
Some people do try to keep these in a community setting, but this isn't advisable, and you certainly wouldn't get away with any of the suspected parent species in a community tank. Parrots are capable of swallowing smaller tankmates if they can catch them so only mix them alongside medium or large peaceful fish. The best tankmates would be robust barbs, catfishes, loaches and smaller Central American cichlids, such as the Cryptoheros or Thorichthys species.
What should I feed them?
Parrots are easy to keep and take most foods including flakes, pellets and frozen foods, such as bloodworms, brineshrimp and mysis.
Why don't they keep their bright colours?
This might depend on the variety of Parrot cichlid and its colour. Some erythristic (red) forms of Central American cichlid, which these may be descendents of, do change colour naturally as they mature, so this could have been passed on genetically. Some forms of the Red devil and Midas cichlid, for example, have a tendency to become paler with age.
However, perhaps the main reason you'll see a marked colour change in these fish is because they may have been dyed - including most red ones. If you keep the red varities and want to sustain the bright colouration go for a specialist colour food, such as the one from Tetra or Aquarian, and use this as more or less the only food source.
Many of the Parrots on sale here are artificially coloured using special dyes. Practical Fishkeeping has seen photographic evidence which shows the species being injected with coloured dye at multiple sites along the flank. Several injections of coloured dye are made over a period of hours, which produces a diffuse stripe of colour. After a day or so, this colour has spread to produce a fish with a more or less uniform base colour represented by the dye.
We'd recommend avoiding green, blue and bright purple ones. It's extremely unethical to support the trade in dyed fishes. You certainly aren't going to be able to maintain these colours and the fish will quickly fade to a sort of pinky colour. Even if you're not particularly bothered about the ethical issues of artificially colouring a fish, these are a bit of a rip-off, as the colour is ephemeral.
My dealer has some without tails. What are these?
These are called Heart parrots, on account of their heart-shaped body. They completely lack a tail and just have an inward stump at the rear end. Even among open-minded Parrot keepers these are often frowned upon.
According to a recent paper by Svein Fossa, President of the trade body Ornamental Fish International (OFI), these fish are suspected to be produced through the amputation of the tail fin. Practical Fishkeeping has now seen photographic evidence which proves that this species, and some Flowerhorn cichlids are being produced in this manner.
Such acts would be illegal if undertaken in the UK, but oddly it is not illegal for shops to trade in such fish. Please do not support this cruel trade by purchasing such fish.
What about the striped ones?
These turned up on sale at UK stores in 2005. They are available in a number of different colours and are being marketed by unscrupulous wholesalers and retailers as selectively-bred fish, which they aren't. The only in which the fish could have possibly been produced is through the application of a coloured pigment by hand. Other readers have also reported Parrots on sale which have words and smiley faces "painted" upon their flanks.
According to a report we published in the News in early 2006, these fishes are produced using a laser to dye the flanks.
We'd strongly advise you to avoid these, and any shops stocking them, like the plague. We're actively campaigning against the sale of these dyed fish. Indeed, much of the trade involved in the production of various forms of Parrot cichlids is ethically questionable and many prefer not to fund it by purchasing any Parrot cichlids, irrespective of whether they are dyed or not.
Fossa, SA (2004) - Man-made fish: domesticated fishes and their place in the hobby. OFI Journal, Issue 44.
This is an item from the Practical Fishkeeping archives. It may not be reproduced without written permission.
Matt Clarke tells you everything you need to know if you are a new goldfish keeper.
How many should I keep in a bowl?
Erm, none... These days, goldfish bowls are considered very old-fashioned and we don't recommend that you keep any goldfish in a bowl. A proper aquarium is a much better choice if you want to be successful in keeping these fish.
But my aunty Irene had a goldfish for years in a bowl, and it lived until it was about 10.
Your aunty Irene was very lucky! The vast majority of goldfish kept in bowls don't live very long, and while they're there they don't have a very good quality of life.
Although they might only be a few centimetres long when you see them on sale in the shops, goldfish have the potential to get to at least 15cm/6" and sometimes double that, if you get conditions right. It is true, to a certain extent, that keeping them in a confined space might restrict their growth, but this isn't considered a very kind thing to do, and there are risks involved. A nice spacious aquarium will make your goldfish much happier.
What size tank would you recommend for a goldfish?
Given the size that a goldfish can reach, the minimum size you ought to consider is really somewhere around the 60cm/24" mark. This ought to safely house a few goldfish while they're young, but you might need a bigger aquarium (or a pond) if the fish grow very large.
Unfortunately, there are lots of very small tanks on sale which are recommended for keeping several goldfish in which are really much too small to keep them in successfully. You might get away with keeping one, maybe two, in one while the fish are very small if you are a conscientious fishkeeper, but the conditions will be cramped and it will be hard to maintain good water conditions. The fish won't appreciate this much.
I don't need a filter, do I?
A filter is highly recommended, even for goldfish. Fish produce toxic wastes and these can harm your fish if they are allowed to build up. A filter can help to remove them and improves the quality of life for the fish.
Although they are perceived as being as tough as old boots, the modern goldfish is a sensitive thing and will fall ill, become diseased or die if the water quality deteriorates.
Won't a bit of oxygenating weed do the trick?
Sadly, no. We really would recommend that you get a filter. Aquatic plants will oxygenate the water during the day, as part of photosynthesis, but at night they respire and remove oxygen from the water. Also, goldfish are omnivores, and they quite like the taste of aquatic plants so they're quite likely to eat them.
Will an airpump on its own do?
An air pump on its own, without a filter, is betting than nothing, but it's still not going to make conditions that much better for the fish. You really do need a filter if you want the fish to be safe and happy. If you are adamant that you aren't going to spend the few extra pounds on a filter to attach to the airpump, then don't forget that the pump needs to be running 24-hours a day, even if it's a bit noisy.
Most of the tanks I have seen have a plastic grid on the bottom. Is this a filter?
Yes, most basic goldfish tanks come with an undergravel filter. Although these are quite old-fashioned, they do a good job, when you know how to look after them properly. The plastic grid part sits below a couple of inches of aquarium gravel and has a couple of upright pipes sticking out of it. You need to pump air down these "uplifts" using an air pump which sits outside the tank.
The upward movement of the air bubbles inside the uplifts causes water, laden with dirt, to get sucked into the gravel. Dirt, including fish poo and bits of food missed by the fish, gets trapped in the gravel and forms a food source for some special bacteria that live there.
Those bacteria will break down the decomposing gunk and prevent it from polluting the water and making the fish sick.
Are they noisy? Can I turn it off at night?
By their nature, the vibratory air pumps used to power undergravel filters are a little noisy and this might be annoying if the pump is in a quiet room, such as a bedroom.
Unfortunately, it's not a good idea to switch off the pump. The bacteria that live on the filter need a constant flow of oxygen-rich water, and without it, they will suffer and the water could get polluted. You need to keep the pump running 24-hours a day.
How do I clean the gravel if it gets dirty?
Although it seems logical to take out the gravel and wash it under the tap when it gets dirty, this is not very wise.
The gravel sitting on an undergravel filter is covered in trillions of helpful bacteria, and if you wash it, you'll destroy them. Without enough of those bacteria, the filter won't be able to remove the fish's wastes and the tank will become polluted, and your fish could get sick.
Instead of removing the gravel you should invest in a gravel cleaning syphon. These are quite cheap (under a tenner) and very easy to use. All you need to do is start the syphon up, either by sucking on it, or filling it with water, and then hold the free end over a bucket.
If you plunge the gravel cleaning part into the gravel, you'll see the gravel swirl around. The dirty water will get sucked into the bucket, but the gravel should remain in the tank. You simply need to "vacuum" the bottom of the tank once a week and your tank will look sparkling all the time.
Can I just top up with tapwater?
Nope. Tapwater contains chlorine (and possibly chloramine, depending on where you live) and is toxic to fish, and to the vital bacteria living in the filter. Before adding any new water to the tank you must treat it with a special additive called a water conditioner or dechlorinator.
All shops sell these products, and they only cost a few pounds for a bottle, so it's not particularly expensive to use. When you top up, just put the recommended amount of conditioner into the bucket of tapwater, give it a swirl around and then slowly pour it into the aquarium.
What about an internal filter, instead?
Internal filters are also very good, but you need to be careful when cleaning them. These filters sit inside the tank and usually have a small water pump on the top which sucks dirty water into a sponge.
The sponge traps dirt and debris, like the gravel in an undergravel filter, and also acts as a home for those friendly bacteria. The sponge must never be washed under the tap, as the chlorine present will kill the bacteria that allow the filter to remove chemical toxins from the water.
Instead, turn off the filter, remove the sponge, give your gravel a vacuum with a gravel cleaner and rinse the sponge in the dirty water. This will ensure that the bacteria stay alive.
Sponges eventually need replacing, but it's vital to remember never to replace the whole sponge all at once. You're supposed to chop it in half and replace one half one month and the other old half the next!
Not many of the "goldfish" I have seen look like the normal variety. Are there lots of different species?
No, there's only one species of goldfish - Carassius auratus, but over the centuries many different varieties have been selectively bred. Many of these look quite unlike the stereotypical common goldfish.
The common goldfish, the comet (this has a pointy tail) and the shubunkin (which is blue and speckled) are the most widely seen of the straight-tailed varities. These are generally robust and easy to keep and grow fairly large.
The so-called fancy goldfish, which have round bodies, long flowing fins and often deformed eyes and things, tend to reach smaller adult sizes and are much more sensitive fish. Quite often, the fancy varieties tend to suffer from illnesses, especially bacterial infections, if you don't keep their water in really good order.
Can straight-tailed goldfish and fancy goldfish be kept together?
You can keep them together, but it's best to keep them separately. Straight-tailed fish are faster swimmers and can be boisterous, whereas the fancy ones aren't so great at swimming and tend to wobble about a bit. You might get the odd straight-tailed goldfish that bullies a fancy one, too.
Why do they float around on top of the water sometimes?
This is caused by a problem with the fish's swimbladder - an internal gas organ which is used to control its buoyancy.
Lots of different things can cause the swimbladder to go wrong, and these can make the fish float or sink, depending on what's happened. It's virtually impossible to tell the cause in most cases, so you need to try and work it out via a process of trial and error.
Dried foods can sometimes swell up in the gut and cause buoyancy problems. Try offering less dried foods, especially pellets, or offer some daphnia which is believed to act as a laxative.
If that doesn't work, have a look at the Interpet Swimbladder Treatment. This is aimed at killing bacteria that can cause a swimbladder disorder, and it's worth a shot.
If either of those don't work then it's quite likely that the problem is a genetic one, for which there will be no cure. Fancy goldfish have their internal organs squashed into a very unnatural position and this means that swimbladder problems are rife in these fish. In most cases, swimbladder problems aren't particular cause for alarm, but if your fish looks like it is suffering please consult your local fish vet.
What should I feed them, and how often?
Most people feed their goldfish on dried flakes or pellets designed specifically for goldfish. Good quality ones, such as those from the major manufacturers, such as Tetra, Aquarian and Hagen, are very well-researched and will provide everything the fish needs in its diet.
As a treat, you might also like to offer some frozen foods such as Daphnia, bloodworms or maybe a couple of squashed frozen peas.
Most goldfish will be fine on just one or two small feeds each day. Don't feed the fish more than they will eat within a couple of minutes. If there are flakes floating round in the tank after a couple of minutes, you've been adding too much and you're likely to end up with polluted water as a result.
What other fish can I keep with goldfish?
The choices of fish that can be kept with goldfish in an aquarium are becoming more limited, as new legislation has made it illegal to keep certain species of coldwater fish without a special licence.
In an aquarium, some of the commonly sold coldwater fish, such as Koi, sterlets, Golden orfe and Tench, aren't really suitable because of the large size they reach, so choices are restricted to those species which remain small and don't nip the fins of goldfish.
Weather loaches, Misgurnus anguillicaudatus, are a nice choice if you have a tank of 90cm/36" or more. They're peaceful, a little unusual and very placid, and mix without problems.
Rosy red minnows, Pimephales promelas, are also a pretty safe choice, and they remain small at just 10cm/4" tops.
White Cloud Mountain minnows, Tanichthys albonubes, will mix with very small goldfish, but once mature, adult goldfish are capable of eating the minnows.
How long can goldfish live?
Anything over 10 years is quite reasonable, but many fish will live for several decades. The record is thought to be somewhere around 40-years old. That's not bad value for money when you consider that these fish only cost a pound or so, but it should also make it clear that goldfish are, like any other pet, a long term committment and shouldn't be purchased without proper consideration.
Do I need a light?
A light isn't strictly necessary for goldfish, other than for aesthetic reasons. In a tropical aquarium a light is needed to provide plenty of light to help the plants grow, but goldfish tend to eat most plants.
That said, an aquarium without a light will look pretty dull and boring, so you'll probably want to add one anyway. This should only be left on for about eight hours each day, otherwise you'll find that the glass quickly gets covered in algae.
How much should I pay?
A bog standard common goldfish of about 3cm should cost around one pound. The fancy varieties, which have round bodies and draping fins generally sell for three pounds at the smallest size. Larger fish and better quality specimens cost more. Some of the best quality Chinese or Japanese fish can cost hundreds, though these are hardly ever seen on sale in the UK as the market for them is rather limited.
Are they a good choice for the beginner?
Yes, they're quite easy to keep. However, they're not as hardy as they used to be, especially if you opt for the fancy varieties with short round bodies. Goldfish also get relatively large, so although many people perceive them as a fish for the small aquarium, this isn't really the case.
Quite a lot of fishkeepers who start with goldfish quickly move on to a tropical aquarium. A tropical community tank is arguably easier to keep and maintain than a coldwater tank, and you'll be able to choose from a much wider selection of small, cheap and colourful fish. There's absolutely no reason why a complete novice, including a youngster, shouldn't start off with a tropical tank. The only additional equipment required on a tropical aquarium is a heater thermostat, which costs around 20 pounds.
This article is exclusive to the Practical Fishkeeping magazine website and was published on 10.28.05
Ever wondered why different temperatures are recommended for different fish? Matt Clarke answers some of the more technical questions relating to temperature and the way it affects your fish.
Are fish cold-blooded?
Sort of. Fish are poikilothermic, so when the water temperature changes so does their body temperature. A few fish, including some catfishes, can change their body temperature, and some tunas and sharks maintain a body temperature a few degrees centigrade above the ambient water temperature.
In what ways does the water temperature affect fish?
Temperature affects a number of physiological processes. For example, pond fish become inactive during the winter months because their metabolic rate slows in lower temperatures.
At higher temperatures, water is capable of holding less dissolved oxygen. As fish have a greater demand for oxygen at higher temperatures, the end result is breathing difficulties or oxygen starvation.
Rapid temperature changes effect the bodily functions of fish and can be harmful, particularly to those adapted to specific temperatures, such as cool, well-oxygenated rivers.
How sensitive are fish to fluctuations in temperature?
Fish can detect small changes in temperature - some as small as 0.03C. Some fish succumb to whitespot and other stress-related diseases, while others tolerate change fairly well, as long as it's gradual.
Marines, fishes from large stable ecosystems like big lakes, and those adapted to cool water (or very warm water) are generally least tolerant of fluctuations.
As fish species have evolved to live at different water temperatures, each has a different tolerance. The maximum tolerable temperature is called the Upper Incipient Lethal Temperature (UILT) and the minimum is called the Lower Incipient Lethal Temperature (LILT). However, some fish are "eurythermal" and can tolerate a wide range of temperatures.
Goldfish, for example, can live in water from 1-40C/34-104F providing they are properly acclimatised. Other species, are "stenothermal" and have a narrower temperature band.
Kept at the wrong temperatures, fish will become stressed and may fall ill or die. If the temperature is too close to the LILT the fish suffer from hypothermia, and if it's too close to the UILT they suffer from hyperthermia.
In many cases the LILT and UILT change as your fish mature, which is why fry and young fish are much more sensitive to changes.
Can any fish tolerate extreme temperatures?
A few fish are capable of withstanding very high water temperatures. Some killifishes from the Death Valley area live in water up to 45C/113F, and some tilapiine cichlids can safely swim through hot springs of 70C/158F. Few can survive long periods in water over 45C, as their proteins begin to denature above this level.
Lots of fish can tolerate very cold conditions, too. At both poles, fish have developed special biological antifreezes, based on glycoproteins, which stop them freezing when the seawater drops below zero.
Interestingly, the notothenioids at the Antarctic and the cods at the Arctic have evolved almost identical antifreezes independently. Many polar fishes are so well adapted for life in the freezer that they die at temperatures of just 5C/41F.
What if my fish start overheating?
Because fish need more oxygen when they are warm (and warm water holds less oxygen), they usually succumb to oxygen starvation. Boost oxygen levels by adding extra aeration and bring the temperature down by placing bottles of cold water in the tank, or conducting a small water changes and topping up with cold dechlorinated tapwater.
What "tropical" fish can I keep in coldwater?
Although some tropical fish, like certain Corydoras, can tolerate slightly lower temperatures than normal if slowly acclimatised, the process could be stressful, so experts don't recommend it.
We could probably survive fairly well sleeping outdoors without any bedding, but we'd probably find the experience rather uncomfortable and would soon catch a cold or flu. You should try to keep your fish under conditions they would experience in the wild.
Should I top up with water the same temperature?
You should ensure that replacement water is close in temperature to the water in the tank. However, topping up with cold water can trigger many fish species into spawning if the fish have been conditioned.
As sea temperatures don't fluctuate as much, replacement saltwater should be the same temperature as that in the tank.
How long does it take new purchases to adjust?
While it can take fish a long time to truly acclimatise to a new temperature (or different chemistry), research shows that floating fish bags on the water surface for a few minutes prior to unpacking increases their resistance to thermal stress. A polystyrene fish box or picnic hamper is useful for keeping new purchases warm (or cool during summer) on your way back from the shop.
This is an item from the Practical Fishkeeping website's archives. It may not be reproduced without written permission.
Ammonia can be a real danger to your fish, as Matt Clarke explains.
What is ammonia?
Ammonia (NH3) is the most toxic nitrogenous waste found in the aquarium and is capable of quickly killing fish, or causing them to become diseased. It's produced in the breakdown of organic materials, and by the fish themselves as a by-product of their metabolism. In fact, the vast majority of ammonia is excreted from the gills of your fish.
Why is it dangerous to my fish?
Ammonia affects the gills and blood of fish and the fish produce extra body and gill mucus to relieve the burns it causes. Extra mucus covers the gills, and reduces the ability of the fish to absorb oxygen.
Ammonia is also directly toxic, and may reduce the ability of the haemoglobin in the fishes' blood to retain oxygen.
How is it normally broken down?
Under normal circumstances, when the biological filtration is mature and functioning correctly, beneficial bacteria in the filter will utilise ammonia as an energy source and turn it into nitrite. Other bacteria then use the nitrite and churn out nitrate, which you need to remove by changing some of the water each week and topping up with dechlorinated tapwater.
What are the symptoms of ammonia poisoning?
Since ammonia tends to affect the gills first, gasping is one of the first things you'll notice. Fish may gasp at the surface where the oxygen level is greatest, or lay on the bottom, conserving energy but breathing heavily.
You may also see them holding their fins tight against the body, scratching against objects in the tank, or if you spot the problem late, you may notice that they have succumbed to disease.
How do I know if ammonia is present?
The only way you can detect ammonia is to use a proper test kit. Get into the habit of testing your water weekly for ammonia, nitrite, nitrate and pH, and check again if your fish look unwell or are acting unusually. A single ammonia test kit can cost as little as 5-10, but you can buy a master kit covering the four most important ones for 15-20.
What causes the ammonia level to rise?
There are lots of different reasons why ammonia levels might rise. Here are some of the most common things you need to investigate if you detect ammonia in your test results.
- New tank with insufficient bacteria.
- Filter has been washed in tapwater or an old sponge has been replaced.
- Disease treatments have killed the filter bacteria.
- Insufficient filtration.
- Tapwater has not been treated correctly (chlorine or chloramine).
- Too many fish added too soon.
- Dead fish decomposing in the tank.
- Uncured living rock.
What is ammonium?
Ammonium, NH4, is a less toxic form of ammonia. When ammonia is present in your water, some of it will be deadly free ammonia, NH3, and some of it will be less toxic ammonium, NH4. The amount of each present depends on the pH and temperature of the water.
How do I interpret my ammonia test results?
Bizarrely, most of the test kit manufacturers omit some vital details from their test kit instructions, presumably to make things a little less confusing for the tester. For a start, all aquarium test kits measure the presence of something called Total Ammonia Nitrogen (TAN) and not solely ammonia, as you might think.
Total Ammonia Nitrogen is made up of ammonia and ammonium, and the proportion of each that is present in your water will depend on its temperature and its pH. To find the real ammonia level you need to use a special look up table, which again isn't provided with most test kits, and compare the pH, temperature and TAN level to the figures on the chart.
What is a safe level for ammonia?
There's no "safe" level, as the presence of any ammonia is cause for concern. You ought to try and find out why ammonia is present as soon as you find it, and then take measures to remove or dilute it as quickly as you can.
What should I do if I detect ammonia in my water?
How you tackle the problem depends on the cause. You may have to do a bit of detective work to find out what you've done wrong. But first undertake an immediate large water change. Make sure the new water is dechlorinated and of the same chemistry and temperature.
If ammonia continues to increase, monitor the tank closely with your test kits and do additional water changes to keep the levels low.
Nitrite levels may also rise following an ammonia problem, so be ready to dose your aquarium or pond with salt (at about 1-3g per litre) to reduce its toxicity to your fish.
It helps considerably if you can add something to the water, or the filter to remove or neutralise ammonia.
How do I make ammonia less toxic?
The quickest thing to do is to conduct a large partial water change and top up with dechlorinated water. A lot of people might tell you that you should be careful not to change too much water when you do this, advising perhaps just 35%, to avoid upsetting the fish. My personal opinion is to ignore this. If ammonia is present at a toxic level you need to get rid of it fast. I wouldn't have any concerns about changing 50% or more of the water to sort the problem out temporarily.
What is zeolite and why might it help me?
Zeolite is a natural crystalline mineral (hydrated aluminosilicate), formed millions of years ago when volcanic ashes were deposited on the floors of alkaline lakes.
The one we use, clinoptilolite, is one of over 40 different zeolites. It can remove certain ions from the water, such as ammonium, phosphate and calcium, via two processes: adsorption and ion exchange.
In ion exchange, ammonium and other ions are taken in and exchanged for sodium from the zeolite, and locked away safely. When it's full, you remove it from the tank or pond and soak it in saltwater. Ammonium and other ions are swapped back for the sodium in the salt, and after a rinse it's used again.
It also removes the same ions by adsorption, but this can result in some of the ions, including ammonium, being released back into the water at a later date. So zeolite won't last forever and can only be recharged and remain effective so many times.
It's an effective solution in emergency ammonia situations, but keep testing and making water changes, because it's not removing the free ammonia, just the ammonium. You may need to recharge it daily, so buy two bags and recharge alternatively.
It's less effective with increasing pH and hardness, and won't work in water that contains salt. Bulk zeolite for pond use can be picked up very cheaply, often for as little as 10-15 for 10 l.
This article is from the Practical Fishkeeping website archives.
Fish disease outbreaks need to dealt with promptly, but how do you know what it is? Andy Gordon answers some of the most common questions on diagnosing and treating common aquarium fish diseases.
A fish has died unexpectedly, does this mean there is a disease in my tank?
Even the best kept fish can fall victim to ill health. It doesn't necessarily mean that there is anything wrong with the aquarium when this happens and one of the worst things that you could do in this situation is subject a tank full of fishes to a whole battery of inappropriate medications. Some medication is toxic to some fish and to some invertebrates, adding these medications could easily make things worse.
It could be that a fish has died from an age related illness or trauma (injury) in which case there is absolutely no need to treat the aquarium at all since neither condition is contagious and the only victim is already dead.
Before using any medication in an aquarium or pond, the first thing to do is to try to diagnose exactly what the problem is. This can be done by carefully observing the fish and then listing all the symptoms. You should be able to determine the probable cause of the disease by reading about the most common ailments in this article.
Once you have the diagnosis and you are reasonably confident that it is the right one you can choose the right medication using the Treatment Finder on this website.
What do I need to know about medication before using it?
- Unless specifically advised to do so, never use two or more aquarium remedies at one time. Different remedies can still contain some of the same ingredients and if two remedies are used it could lead to an accidental overdose of some ingredients and this could be toxic to the fish.
- Check what the realistic volume of your aquarium is allowing for displacement and the fact that it isn't filled to the absolute top. Failing to do this could render the treatment useless because you won't be using an accurate dose.
- Check that you can use the medication with all the species in your aquarium or pond. Some species don't tolerate medication very well and in some cases its use can be fatal. Mormyrids (Elephant noses), Orfe, sharks and rays, loaches, corals and other invertebrates are all known for their lack of tolerance of certain medications. Always read the instructions before dosing, and before purchasing the treatment.
- Some medications are specific to either freshwater or saltwater. These are only intended to work against specific ailments found in that environment and because of this they will at best be ineffective if used wrongly and at worst they might even be toxic.
- Some medication is toxic to humans, take care when handling these products and wear some protective gloves to prevent accidental contact with your skin.
- Prompt treatment is usually more successful than treatment which has been put off for a few days. Attacking infections during the early stages is much simpler than trying to tackle a well established infection.
What kinds of diseases might I come across?
There are lots of organisms waiting for the chance to attack a fish. They can be split into different groups each requiring a slightly different approach to treatment and after care. They are: fungal diseases, bacterial diseases, and parasitic infections.
What are the signs of a fungal disease?
The spores of various fungi are always present in an aquarium. Normally fungus doesn't attack a healthy fish because the mucus which covers a fish fights off infection. But if a fish becomes injured through bumping into a sharp object, rough handling or an attack by another fish, or if it has become stressed due to a poor environment, then the fungus could take advantage and gain a hold. Once the fungus as gained entry past the fish's natural defences it will spread and weaken the fish further unless treated.
How will I recognise fungus on my fish?
Fungus (see top picture) is often given the common name of 'cotton wool disease' this is because the fungus looks just like cotton wool attached to the fish. It can vary in colour slightly from almost white to grey, it may even appear green if algae gets in amongst it too. Although this doesn't look too serious it actually is. Under the 'cotton wool' the fungus is eating away at the fish's tissue, so fast treatment is essential.
How can I tell if my fish have a parasitic infection?
Protozoa are the most common parasites that we come across in the aquarium. They are microscopic organisms and part of their life cycle is spent on, or even in, a fish. They can be very infectious in the confines of an aquarium where new hosts are easy to find.
Most are easy to treat, and if treatment begins early enough the prognosis is generally quite good. Protozoan infections irritate the fish and make them itch. This results in a lot of the fish scratching against objects in the aquarium and is one of the first signs to look for when trying to diagnose a protozoa infection, along with rapid breathing and clamped fins. If the infection is very heavy the fish may become quite lethargic and if untreated most will weaken the fish to the point of death.
What kind of protozoa infections am I likely to see on my fish?
- White spot: If your fish have white spot you will see lots of pin head sized white dots spread randomly all over the fish's body and fins. All parts of the fish will be affected, this is important because you may notice some tiny white dots on your goldfish and assume that it has white spot but that might not be the case. Male goldfish develop tubercles at certain times of the year, these show that the goldfish is in breeding condition. The tubercles will be restricted to the gill covers and around the pectoral fins and no where else, obviously this requires no treatment.
- Velvet: Velvet is another protozoan infection. Unlike white spot it is less noticeable because the spots are much smaller and more closely packed together. The velvet parasite uses photosynthesis for part of its nourishment and it contains chlorophyll to achieve this. The chlorophyll in the protozoa gives infected fish a distinct appearance and infected fish have a characteristic gold or yellowy green caste to them.
- Slime disease: There are several protozoa responsible for causing slime disease. As part of their natural defence fish produce mucus to fight off external parasites. When a fish is infected with the protozoa which cause slime disease you will see lots of excess mucus being produced. So much is produced that it may be seen hanging from the body and it is this which the condition is named after.
- Neon tetra disease: Despite the name this parasite can infect lots of tetras, rasboras, danios and other small fish. Unlike some other protozoan infections which remain external the protozoa which causes Neon tetra disease (Pleistophora hyphessobryconis) attacks the muscle and tissue of the host. Some fish appear to develop a natural immunity to this infection after being exposed to it. Once symptoms can be seen then there is not believed to be an effective cure. The features of this disease are very slight to begin with, there may be a small area where there is a loss of colour. This is followed by localised wasting and finally by a kink developing where the wasting was, shortly after this the fish will die. Fish showing symptoms of the disease should be isolated to help prevent the disease from spreading.
- Marine ich: This looks very similar to white spot seen in fresh water fish and the two parasites are closely related. In a fish-only aquarium this is relatively simple to treat, but in an aquarium containing invertebrates it can prove very difficult. Buy only quarantined fish since prevention is the best option.
Are my fish suffering from a bacterial infection?
Bacteria are ever present in both ponds and aquaria. These are mostly harmless unless the fish are stressed in some way, as stressed fish fall victim to all kinds of infections more easily than they normally would. Any of the following could be an indication of a bacterial infection: open sores, ulcers, sudden unexplained deaths, frayed or blood streaked fins, areas of raised scales, cloudy eyes, pop eye and wasting.
What kind of illnesses can bacteria cause?
- Ulcers: Ulcers are deep open sores on the skin. Strangely, affected fish seem to be able to carry on as nothing is wrong, but don't assume that this is the case. Ulcers are very serious and life threatening. They can lead to osmotic problems for the fish so particular attention has to be paid to the overall environment along side any medication.
- Fin rot: Fin rot usually occurs when a fish is kept in poor conditions. The fins and tail become streaked with blood and they begin to fray. The tail is usually most affected and will gradually get smaller as it rots away. If the infection reaches the body the result can be fatal. Look out for frayed fin edges (not one simple split), reddened or blood-streaked fins.
- Mouth rot: Mouth fungus or mouth rot, despite its name, is in fact a bacterial disease and is normally restricted to the mouth region. The bacteria responsible form long strands in large colonies which makes them look very similar to fungus. If you see a case of fungus which is restricted to the mouth region then it is most probably mouth rot and should be treated as such, and not with a fungicide treatment. Prompt treatment is required if the fish is to be saved.
- Wasting disease: Wasting disease is also known as Fish TB. The infected fish can display a whole range of symptoms with wasting, pop-eye and ulcers being the most common signs of infection. This can be a stubborn disease to treat and typically needs professional advice and a course of antibiotics. Veterinary help should be sought if you suspect this condition because under some circumstances it can be passed on to humans. Although not fatal it will require a long course of antibiotics.
- Pop-eye: As its name suggests pop-eye can be recognised quite easily because the eye swells and stands proud from it's socket. Dramatic as this looks if the cause is fixed the eye will return to normal, often with no treatments being used. There is more than one cause for this symptom. It can be caused by a bacterial infection or simply through the fish being kept in a poor environment. By poor environment this could be poor water quality (ie. pollution) or the wrong water chemistry. Before resorting to an unnecessary course of treatment it is worth checking the fishes environment and correcting any issues there. If the environment remains poor then any treatment is likely to fail.
- Infected wounds: Occasionally small wounds and abrasions can become infected. You may notice a reddened area or a small area of raised scales or even just a single scale. If the fish is other wise healthy then prompt treatment is usually quite successful.
It is worth noting that well established bacterial infections may only respond to proper antibiotics prescribed by a vet. Early treatment is therefore essential in order to have any chance of a successful outcome.
I have some inverts will they be safe if I medicate the tank?
In some cases, no. Marine and freshwater inverts can be harmed by some of the ingredients used in some treatments, particularly copper-based ones. Some manufacturers take this into account and make an alternative medication which is safe to use with inverts.
Are there other ailments which aren't covered here and if so why is that?
There are other diseases and ailments such as viral diseases and physiological disorders for which there are no treatments available. Some common viral diseases such as Lymphocystis don't require any treatment because after showing some symptoms the fish usually develops a natural immunity and the condition clears.
Other conditions don't respond to simple treatments. Organ failure, tumours, or internal damage obviously can't be repaired with the addition of a few drops of some aquatic potion. Either seek professional advice or consider euthanasia if the fish is really suffering and has no quality of life.
Is there ever a time to when not to treat?
Yes, in some instances when a fish is sick beyond any hope of recovery i.e. when it is suffering with advanced tumours or other incurable disease and it is obviously suffering then the kinder thing is to intervene to end the suffering. Look at it as a final act of kindness for an old friend.
How do I select the right treatment?
Once you have made your diagnosis, you need to treat promptly, ideally after testing the water and correcting any water quality issues. Selecting the right treatment can be tricky, particularly if your tank houses invertebrates or sensitive fish that may react badly to certain medicines.
Where can I get more help?
You could post your query, along with a photograph of the fish and some water test results, on the PFK forum, where our members will be happy to help you. Alternatively, you could seek further advice from a specialist retailer, fish health professional or vet with experience in fish.
This article was written exclusively for the Practical Fishkeeping magazine website.
Matt Clarke answers some of the most common questions about buying aquarium and pond gear online, and points readers in the direction of some specialist dealers.
Why buy online?
As online shopping has grown in popularity, so too has the number of aquarium stores offering their goods over the Net. For those who neither have the time, transport or inclination to travel miles to visit their preferred store, online aquarium retailers are a welcome addition.
Although we all like to visit shops to buy certain things, particularly livestock, in a real bricks-and-mortar shop, growing numbers of people are buying their gear online. And as a result, an increasing number of retailers are branching out and realising that it's relatively easy to set-up an ecommerce side to their business.
Recent polls by Practical Fishkeeping have shown that fishkeepers are very price conscious. When we asked "Is fishkeeping equipment too expensive?" a massive 76% said "Yes". Likewise, a few years ago when we polled readers on their buying habits, 65% already shopped online. I wouldn't mind betting that this figure is now a little higher.
You can often choose from a greater range of products than those held in your local shop, and they're virtually always available at much lower prices, so there are some bargains to be had if you want to shop around and seek them out.
That said, the aquarium trade wouldn't be sustainable without bricks-and-mortar stores, so you should still support them as much as you can, too.
Is buying online any different to buying in a shop?
When you buy online from a UK-based company many of your rights are much the same as they are when you buy from a shop.
Just as in a normal shop, goods need to be clearly described. After you've purchased you should also get a confirmation email detailing what you've purchased, so you can contact the store if there's been a mistake with the order.
You're also entitled to a cooling off period that you don't get in a normal shop. If you don't like something for whatever reason, you can send it back to the shop and get a full refund.
New regulations introduced on January 1st this year also state that by law online retailers need to include their postal address, VAT number and company number, where applicable, on their site. Most also provide a telephone number. If they don't, you should perhaps wonder why.
How do I know my transaction will be safe?
Using your credit or debit card to purchase goods online is probably just as safe as it is buying goods in a shop, but there are some things to look out for.
There is as yet no equivalent to Amazon.com for the aquarium market, and most of the companies trading in the UK are relatively small. As a result, they tend to use specialist third-party merchants - such as banks - to handle transactions.
The products are displayed on their normal, insecure websites, but when you make your payment you'll normally be transferred to a merchant site, such as Worldpay, which is owned by the Royal Bank of Scotland.
When you hand over your credit card details your details should be encrypted with a technology called Secure Sockets Layer (SSL), which keeps them away from prying eyes when they're travelling over the Net.
Before you enter your card details, check that the address starts with https:// and not http://. You should also see a little padlock icon in your browser, and if you're using Firefox, the address bar might also change colour to indicate that you're using a secured connection.
It doesn't matter if the site you are shopping on is not itself secured with SSL, so an http:// address on that is fine (and the norm) if you're not providing highly confidential data, like your card details.
Some of the more sophisticated sites take payments seemingly within their own site. Providing the address starts with https:// you should be fine.
How can I be safer when shopping online?
The shop you're buying from might be as secure as Fort Knox, but that won't make an iota of difference if your computer is insecure. Use an up-to-date browser, like Firefox, and make sure that your computer is trojan- and virus-free with all of the latest software updates. Make sure you've got a firewall switched on.
How can I get extra protection?
Use a credit card. If you're spending over 100, you might get protection by the Consumer Credit Act if there's a problem. If you've purchased stuff from an overseas company it can be more difficult to sort things out, so we recommend sticking to UK businesses where you can.
Are the goods always in stock?
A lot of companies do not hold all of their goods in stock. When you place your order for, say a massive metal halide lighting system, they might then order that from their supplier, who will deliver it to you from their warehouse.
What happens if I want to return something?
Under the UK Consumer Protection (Distance Selling) Regulations, you get a seven day cooling off period and you can send things back. Traders are allowed to define procedures for returns, which need to be supplied.
The cooling off period doesn't apply to , magazines, DVDs or perishable items - including livestock, one would guess.
If you've ordered something massive, like a pre-formed pond, and it needs to be collected, you could be charged for the cost of having it collected.
Check out the company's website if you need to make a return, and drop them a line to arrange its return. If you're posting it, get proof of postage from your Post Office, and make sure you get it insured. The Post Office sometimes lose things...
What happens if my order doesn't turn up?
Online retailers should give you an indication of when your order is supposed to be turning up. If it doesn't arrive by the date you agreed when you ordered, you can get a full refund. If the shop doesn't or can't state a date for delivery, you have to wait 30 days before you're entitled for a refund if it fails to materialise.
If goods don't turn up, it's always worthwhile dropping the store a line. Keep a record of what was said or emailed, just in case. If you have difficulties with your transaction, your best bet is to contact the Citizens Advice Bureau (CAB) for expert advice.
Can I buy livestock online, too?
Yes, a number of suppliers are now offering fish and invertebrates online. Aquarium and pond plants have been available this way for decades. It's important to double-check delivery times if you're buying livestock, as you need to be around to unpack the box when it arrives.
If you're buying fish, you should also check whether heat packs are included, and what method is being used to send the fish. Couriers are fine, but the Royal Mail doesn't allow fish to be sent by post, so do check this before you order.
Always use your common sense. Don't order fish when it's really hot or really cold, and don't buy things on impulse.
Where can I find online retailers to buy stuff from?
The Featured sites section of the Practical Fishkeeping website is a very good place to start.
There are lots of specialist online aquatic shops listed here, so if you check through the listed sites here and elsewhere in the Directory section you should be able to find some bargain deals.
This article is exclusive to the Practical Fishkeeping magazine website and may not be reproduced in any format without written permission.
Matt Clarke answers some of the most commonly asked questions on the scientific names of fishes?
Why do we need scientific names? What's wrong with using the common name?
There's only ever one scientifically valid scientific name for any given fish species, but there can be many more common names for the same fish. Take the guppy, Poecilia reticulata, for instance. These are just some of the common names listed for this species by FishBase.
è™¹é®° (Mandarin Chinese)
å”é›€èŠ±é®° è™¹é®°,å”é›€éš å¼•é€² (Mandarin Chinese)
Ð³ÑƒÐ¿Ð¿Ð¸ Russian Fed (Russian)
Bandera Ecuador (Spanish)
Barbados millions India (English)
Barrigudinho Brazil (Portuguese)
Barrigudinho-mexicano Brazil (Portuguese)
C bay mu Viet Nam (Vietnamese)
Cytrynwka Poland (Polish)
Gup Netherlands (Dutch)
Gupi Ecuador (Spanish)
Gpi Brazil (Portuguese)
Gupik pawie Poland (Polish)
Guppie South Africa (Afrikaans)
Guppies Trinidad Tob (English)
Guppii Japan (Japanese)
Hung dzoek ue Hong Kong (Cantonese)
Ikan seribu Indonesia (Malay)
Lareza tripikaloshe Albania (Albanian)
Lebistes Brazil (Portuguese)
Lepistes Turkey (Turkish)
Mexicano Brazil (Portuguese)
Miljoenvis South Africa (Afrikaans)
Miljoonakala Finland (Finnish)
Million fish Kenya (English)
Millionenfisch Germany (German)
Millions Trinidad Tob (English)
Poisson million Fr Polynesia (French)
Queue de voile Canada (French)
Rainbow fish Trinidad Tob (English)
Sarapintado Brazil (Portuguese)
Sardinita Venezuela (Spanish)
Wilder Riesenguppy Germany (German)
ivorodka duhov Czech Rep (Czech)
ivorodka dhov (gupka) Slovakia (Slovak)
If I told you not to keep Poecilia reticulata alongside Puntius tetrazona, you'd know which fish I was talking about, or you'd be able to find out. You probably wouldn't if I had told you their common names, particularly if you live somewhere other than the UK.
Scientific names provide a universal language for scientists, and other people, to effectively communicate with each other about any species without fear of getting confused by the language barriers.
Why is a person's name and a date sometimes written after a scientific name?
Any names and dates written after a scientific name refer to the person (or people) who described it, and the year in which it was first described. For example, Puntius denisonii (Day, 1865) tells you instantly that this is the fish was described by Day in 1865.
What do the brackets mean around the author's name and the date?
The brackets, or parentheses, around the author name and the dates show that the species was described under a different name to that which the fish currently has.
For example, Puntius denisonii (Day, 1865) shows that the fish was described by Day in 1865 by under a different name. This name is a synonym and can be found by checking an authority such as FishBase to see the name the fish was original described as.
P. denisonii was originally described as a Labeo species, but got moved to a new genus when another scientist found that Day had got it wrong.
If you check the synonyms table for Puntius denisonii in FishBase you'll find the full taxonomic history of that species, showing all the names the fish has gone under, including misspellings and misidentifications by scientists.
Is it important to add the author name and date?
It's usually dropped for brevity, but it can sometimes be important to know this, particularly if there have been taxonomic rearrangements or other problems with that particular fish. If you're going to write the author name and date, the presence of parentheses is very important.
Take Megalechis thoracata as an example. Normally known as the Port hoplo, and previously known as Hoplosternum thoracatum, this fish has a really messy taxonomic past, and you'd have no idea what fish I was talking about if I didn't tell you the author name and date.
In December 2005 it was essentially renamed following a study by Reis, Bail and Mol. They found that the fish we know in the hobby as Megalechis personata was actually Megalechis thoracata, and that the real Megalechis thoracata should actually be called Megalechis picta. Confusing, isn't it?
With the author name and dates things become a bit clearer. Megalechis thoracata (Valenciennes, 1840) is now known as Megalechis picta (Valenciennes, 1840) and Megalechis personata (Ranzani, 1841) is now called Megalechis thoracata (Ranzani, 1841). FishBase is currently out of date.
Now if I told you I had some Megalechis thoracata (Ranzani, 1841) you'd know that I was talking about the Tailbar hoplo (formerly personata) and not the Spotted hoplo (now picta).
Why are they written in Latin?
Latin was chosen because when scientific names first originated in the mid 1700s, Latin was the universal language used by scientists. Scientific names were, more or less, first formulated by a Swede called Carl von Linne, who loved Latin so much he even latinised his own name - Linnaeus. You'll see Linnaeus written after loads of different fishes' scientific names, as he also described a lot of fish species.
Why are they written in italics?
Scientific names, or rather the genus, species and subspecies, should always be written in italics, or if you're writing on a piece of paper, underlined.
Other taxonomic heirarchies such as family names, like Cichlidae, or their anglicised equivalents, like cichlids, are never italicised.
What's a cheironym?
A cheironym is a sort of working title for a species that has yet to be formally described. The aquarium trade is full of fish that nly have cheironym-based names and they're typically written as something like Puntius sp. "High Fin", with the cheironym part in non italic text inside double quotes. This species has just been officially named Oreichthys crenuchoides.
This article is from the Practical Fishkeeping magazine archives. It may not be reproduced without written permission.
Gravel, sand, specialist planting substrates - there's a lot of choice out there when it comes to what to put at the bottom of your tank. Matt Clarke answers some frequently asked questions about aquarium substrates...
How should I clean my substrate before I add it to my tank?
Although they're often pre-washed, most substrates are very dusty and need to be cleaned thoroughly before they're used, otherwise the tank will turn extremely cloudy.
Washing dusty gravel or sand is messy, tedious and, in winter, rather cold work. The best way to get the substrate clean is to place a small quantity (say a few mugfuls) in a clean bucket and spray water on to it using a hosepipe.
You'll need to keep swirling the gravel around with your hand, and pouring away the dirty water until it runs clear. Then you can tip the washed gravel into another bucket and clean the next batch.
Some substrates don't respond well to being washed in this way, so the more you swirl them, the dirtier the water gets.
Powder-coated coloured gravels are a particular irritation here, so you may as well just get rid of as much of the dust as possible and then just give up, or only swirl very gently.
Laterite substrates are impossible to wash...
How much gravel do I need to buy?
This is harder to work out than you might think, because although sold by weight, it's the depth (or volume) of the substrate that really matters to us fishkeepers, not the weight.
For sand, most people go for a depth of around 2.5cm/1", but with gravel the norm is to go for a deeper layer of say 5cm/2" or more.
The weight of a litre of dry substrate varies from about 1.95kg per litre for fine sand to just 1kg per litre for baked clay substrates. To work out how much you need, simply determine the volume you require and multiply it by the weight of a litre of the substrate of choice.
I've added coloured gravel to my tank and the pH has risen. Why?
Many coloured gravels, particularly the rough textured angular ones with a powdery colour coating, are made from white dolomite. This is a naturally occurring mineral rich in calcium and magnesium, and in its uncoloured form is sold as a substrate for use in marine or Rift Lake cichlid tanks to keep the pH, alkalinity or hardness high.
If you already live in a hard water area, or keep fish that don't mind alkaline conditions such as goldfish, it's not likely to cause any problems. However, it wouldn't be a great choice at all if you want to keep fish that like neutral or soft water - you'll need an inert substrate instead.
How can I keep my substrate clean?
The easiest way to keep the gravel clean is to regularly use a gravel cleaner. In my experience, the battery- or air-powered varieties are invariably much less effective than the cheap, heavy duty syphon-powered ones. The heavy duty Hagen gravel cleaner I bought nearly a decade ago is still going strong, so these are remarkably good value gadgets. I use mine to vacuum my substrate once each week and my tanks always looks clean.
How do I use a gravel cleaner?
Syphon-powered gravel cleaners are designed to remove dirt-laden water from within the substrate when you're doing your partial water change each week. The power of the syphoning water causes the gravel grains to swirl around inside and sucks the dirty water out, but leaves the substrate behind.
Once you get the hang of it, you should be able to vacuum most of the tank floor while only removing about 20-30% of the aquarium water, which you can then top-up with dechlorinated tapwater.
You can start a syphon-powered gravel cleaner in several ways. Since I have inadvertently inhaled several lungfulls of foul tasting aquarium water in the past, I personally prefer not to suck on the end of the hose to get the syphon going - although this is undoubtedly the quickest and most widely used method among fishkeepers.
To start the syphon more hygienically, put your thumb over the end of the hose and submerge the gravel cleaning attachment in the tank on its side. If you quickly scoop up some water inside the attachment and allow it to fill the hose by temporarily removing your thumb a couple of times, you should end up with both the attachment and the hose completely filled with water. Then all you need to do is simply lower the hose end over a bucket and release your thumb. The water should start flowing on its own.
Some substrates are very coarse. What diameter should I go for?
The gaps, or interstices, between gravel grains increase as the grains get bigger, so more dirt may get trapped in the substrate if you use a larger grain size. In contrast, very fine substrates, such as sand, don't allow much dirt to be trapped, so detritus tends to sit on top, where it can be sucked into the filter or syphoned off.
Some fish, including many common species like goldfish, feed by sifting the substrate and eating any food items found within. Many catfishes, like Corydoras, and some oddballs such as rays, eels and mormyrids such as elephant noses, also like to root about in sand.
How can I replace my substrate with something more attractive?
The easiest way to remove the old substrate, without the need to strip down the tank, is to simply syphon it out. If you find a suitable pipe (you'll really need one thicker than the average gravel cleaner hose), you should be able suck up the substrate, the dirt and some of your water.
You can then carefully add your washed substrate to the tank and top up with dechlorinated tapwater that matches the temperature of your tank. The snag with this method is that you sometimes need to remove a lot of water in order to suck all of the substrate out.
You might need to top up and wait a few days before removing the rest to avoid stressing the fish by changing too much water in one go.
Alternatively, you could try removing the remainder with a net.
That white coral sand could give my tropical tank a really marine look. Is it safe to use?
Not unless you want to make your water rock hard and increase the pH of your water to over 8.0. Coral sand and gravel is calcareous, so you should only use it in situations where you want the pH and hardness to be kept high. Many Rift Lake cichlid hobbyists use it to provide the appropriate conditions for their fish.
Those in very soft water areas, such as parts of Scotland, also use small amounts to stop the pH of their aquaria from dropping naturally, something which occurs due to the lack of buffering in their water.
How deep should my silver sand be?
In freshwater tanks, generally only a thin layer of sand is used, since it is so fine that it tends to stagnate if used in a deep layer. About 2.5cm/1" should be plenty in most cases.
I've added an expensive plant substrate. Can I still use a gravel cleaner?
If you use a gravel cleaner in a tank containing a costly planting substrate, such as laterite, you risk sucking it out. If you've got a professional-style planted tank, chances are you'll be dosing with CO2 too, and you'll have a lower stocking density, so this shouldn't be too much of a problem.
What is an inert substrate?
Inert substrates and rocks don't alter the water chemistry, while non-inert, calcareous substrates do. These contain calcium and other minerals that increase the hardness and pH, so if you add them to your tank they'll make the water harder and more alkaline.
Inert substrates are of particular importance to those keeping fishes that like soft water, such as Discus. Even standard pea gravel contains sufficient calcium to boost the pH and hardness, so don't use it unless you want hard water.
Can I use a mixture of grain sizes?
You can, but they'll all get mixed up eventually with the larger grains usually rising to the top. Personally, I think a mixture of different grain sizes looks very natural, especially in a reef tank.
How do I clean sand?
Before it's added, sand needs to be cleaned thoroughly by swirling it around in a bucket of water until the water runs clear. Once it's in the tank it's a doddle to keep clean. I tend to give it a gentle stir with my index finger while holding a syphon hose in the same hand, which allows any trapped particles to be sucked out.
It's impossible to avoid removing some of the sand during maintenance, as it's light and very easy to suck up, so you'll need to top it up occasionally.
Often seen for sale as Hong Kong plecs or Hillstream loaches, these fish are in fact neither catfishes nor the typical cobitid loaches, as Matt Clarke explains.
What is a balitorid?
Balitorids are members of the family Balitoridae. They are small bottom dwelling freshwater fishes from Asia and there are about 500 species in 37 genera. Gastromyzon are the most widely seen in UK shops.
Are they easy to obtain?
The most common ones are usually seen for sale in the coldwater sections of aquatic shops are usually sold as Hong Kong or Chinese plecs. However, they aren't all from China (most are from Borneo), and they are certainly not plecs - they aren't even catfishes, in fact. Some are sold as hillstream loaches, although they aren't true cobitid loaches either. Balitorids are actually a member of the cyprinid order are cousins of the cobitid loaches.
Are all balitorids similar?
No. The family is big and diverse and there are some notable differences between them.
The balitorines (subfamily Balitorinae), or Chinese plecs are the most commonly seen. These have a flat body, underslung mouth and an adhesive organ on the belly formed from their fused pelvic fins.
The Homaloptera-group are more loach-like. Although some experts reckon these should be lumped in with the balitorines due to some shared features. Homaloptera, in general, feed on invertebrates. They probably live in slower flowing water than balitorines like the Chinese plec.
Nemacheilines, could easily be mistaken for "real" cobitid loaches. One of them - the Stone loach, Barbatula barbatula - lives in rivers in the UK.
We've seen quite a few new balitorids in recent shipments from India. If you have a rummage through your dealer's tanks you could find some very unusual fishes.
Do Chinese plecs eat algae?
Balitorines usually feed on aufwuchs rather than the algae itself, so they may not make a huge difference to the amount of algae visible in the tank. Aufwuchs is a collective name for microscopic invertebrates that live within the tufts of algae. Most balitorines will accept frozen bloodworm, brine shrimp and tablet foods or even flakes, but lush green algae is appreciated.
Are they coldwater?
Not as such. Most of those in the shops are really tropical fish. Some have a high requirement for oxygen, and because warmer water holds less oxygen than cold water, they do better in cooler tanks. They are highly unlikely to survive outdoors.
For best results keep them around the 20C mark. If you keep them warmer you'll need to take special care to ensure the water is very well oxygenated.
What conditions do they like?
Many species are relatively small, so any aquarium over 60cm/24" is usually fine. Ideally this ought to have a substrate of fine sand or fine gravel and be furnished with smooth rounded pebbles and small boulders.
Balitorines like Chinese plecs, are designed to live in very fast flowing white water regions. You are unlikely to be able to recreate realistic biotope conditions in an aquarium, but to get as close as you can, add a battery of powerful internal power filters to provide flow and keep the water oxygen rich.
Ideally, the pH ought to fall between 6.5-7.5 - although many will happily go over pH 8 and seem quite adaptable regarding pH and hardness levels. Keeping the oxygen level high is the most important factor.
Other more loach-like balitorids can be kept quite successfully in the average community aquarium. They seem far less demanding and are often pretty easy to keep.
What is their behaviour like?
Balitorids are really interesting fish to watch. Although peaceful, most will defend territories, either to sequester feeding resources like a nice patch of algae, or to keep other fish away from a potential breeding site. Some balitorines chase other fish, especially rival males and non-breeding females, out of their area but I've never seen them physically harm other fishes.
A few of them, such as some Schistura species I've kept, can be a little aggressive and even drive larger fishes out of their territory.
How do Chinese plecs stay attached to rocks?
Chinese plecs and other balitorines are equipped with a ventral sucker-disc. This is a specially modified set of fins that form a suction cup on the underside of the fish. When the fish settles on a rock, it wiggles its fins to push out water and creates a mini-vacuum which sticks it in place.
The fish can slide over smooth rocks, and can even wriggle over wet rocks out of the water still "stuck" to the rock. This allows the fish to feed in very fast-flowing white water.
They can probably feed from places in a river that other fishes can't even get near to because of the speed of the water flow.
The balitorines seem to be very difficult to catch. What's the secret?
Despite their slug-like appearance these fish are capable of an amazing turn of speed. This coupled with the ability to stick firmly to rocks and the aquarium glass makes them virtually impossible to remove from the tank.
To catch them, remove all of the decor from the tank apart from a single rounded stone, and then coax the fish off the glass using a net. Eventually it will stick to the rock. You can then pick up the rock with the fish still attached, while holding the net underneath. As you reach the surface, the fish will drop off and land in the net.
Have they been bred in captivity?
Yes, although like cobitid loaches, they aren't easy to breed and spawning successes are pretty rare. One PFK reader managed to spawn a balitorine species (Pseudogastromyzon cheni) in her coldwater community tank a few years ago and we have heard of some other reports too.
How do you sex balitorines?
It depends on the species. Males are usually more colourful and may have coloured edges to the dorsal fin, which are more drab in females. Some species also develop patches of odontode-like bristles on the head. These are clearly visible in Gastromyzon ctenocephalus, which is sometimes called the Spiny-headed hillstream loach as a result.
How do you breed them?
Balitorines spawn in a depression in the substrate, alongside a pebble or rock. The male wiggles about a bit to excavate a little hollow in the gravel.
Little is known about how to get them to spawn, since most spawnings have occurred by chance. It seems logical that you might be able to trigger them to breed by conditioning them with plenty of food for a couple of months, and then performing a water change using cooler water.
What species are available?
While only one or two species appear on the import lists that the aquatic shops use to order their fish from abroad with, there are actually many more species imported, most of which come in as bycatch mingled in with other fishes from the region.
There are also a number of currently undescribed species on sale in the shops.
To track down the unusual ones you'll usually have to closely study your dealer's tanks. It's very rare to see any balitorids offered for sale under anything other than a made-up common name. While this can make finding particular species a bit difficult, it does make fish shopping trips very interesting, as you never know what you might find mixed in with the common varieties.
This article was published in the August 2003 issue of Practical Fishkeeping.
Salt has been scientifically proven to have a number of benefits. Matt Clarke scours the journals and speaks to industry experts for the latest on the subject.
Many people are very anti-salt. Why is this, and why on earth would you want to add salt to a freshwater tank, anyway?
Unfortunately, there are lots of myths and old wives' tales surrounding the use of salt. While it is sometimes used inappropriately, it does have a number of genuine, scientifically valid uses in the aquarium for treating health problems, tackling water quality problems and minimising stress, especially during transport. Most of these work by salt's effect on the osmoregulation of freshwater fish.
What is osmoregulation? Is it to do with osmosis?
Osmoregulation is the technical term for the physiological mechanism fish use to control the amount of salt and water in their bodily fluids. As the name suggests, it's based on osmosis.
If you are young enough to remember your schooldays, you'll recall that this is the movement of dissolved stuff through a semi-permeable membrane from a strong concentration to a weaker one.
Basically, freshwater fish are saltier than the water they live in, and their skin is semi-permeable. Since there's a big difference between the amount of salt on the inside of the fish and the amount of salt in the freshwater they live in, freshwater fish leak bodily salts and take in water. Of course, this presents two problems for a freshwater fish: taking in salt and getting rid of water.
Osmoregulation tends to not work so well when the fish are stressed or diseased. This "osmoregulatory dysfunction" means that fish find it difficult to get sufficient salts from the water and may have problems getting rid of excess water.
How do freshwater fish get rid of excess water and take in salts?
Getting rid of the water that floods in is fairly easy. You just urinate constantly! Freshwater fish produce vast amounts of urine - some produce their own body weight in wee every three or four days.
If you were, for argument's sake, a 76kg/12 stone Guppy, you'd be able to fill a Juwel Rio 180 with your own urine in about a week!
Taking in extra salts to replenish those lost to the water takes a bit more effort. Freshwater fish use special cells in their gills to take in the salts, such as chloride, that they lose to the water, which helps keep their bodies salty. Adding salt to the water when fish are stressed means that they don't lose as much salt from their bodies. The principle is much the same as a saline drip for hospital patients.
Should salt be added as a routine tonic for freshwater fish?
Some shops and salt manufacturers recommend adding salt as a routine permanent treatment. However, while salt has some advantages, there is no need to dose with salt on a permanent basis. Most experts only advocate this for brackish species.
Leading fish vet Chris Walster says: "Freshwater fish should be kept in freshwater, not any other.
"We have no idea of what effect placing freshwater fish in salted water has from a welfare perspective. We know that if we place freshwater fish in seawater that they will die sooner or later. We simply do not know, even at a low level of salt, whether it irritates the eyes or gills, etc.
"When we swim in the sea, the salt irritates our eyes. Is it the same for freshwater fish? Are there any other unknown effects which occur weeks, months or years later?"
Fish health expert Dr Peter Burgess says he certainly doesn't advocate salt for permanent use: "Unless the species has a natural requirement for salt, then we should not add salt to an aquarium (or pond).
"Tonic salt for freshwater fish is a bit like aspirin for humans: both medicines have many beneficial uses, but neither should be administered routinely just for the sake of it. Bear in mind that most tropical community tanks will contain salt-sensitive species, such as catfishes.
"Salt can be used as a supportive for salt-tolerant species, for example if the fish have severe ulcers or other major skin breaches that can place a burden on the osmoregulatory system. But healthy, unstressed fish do not need this support. Never use salt to compensate for bad fishkeeping!"
Why, then, is salt added to freshwater systems?
When freshwater fish are stressed, they suffer from osmoregulatory dysfunction, which basically means that they lose bodily salts to the surrounding water. Stress causes this salt-water balance system to stop working properly and the fish suffer.
Adding salt to the water in times of stress can help minimise salt losses by the fish. It can also reduce the toxicity of pollutants and may kill some pathogens.
What problems can low doses cause?
Dr Peter Burgess told us: "I have heard that salt can damage pond plants and, of course, it can only be removed by the diluting effects of water changes. Also, the prolonged use of salt can make some pond fish parasites (eg Trichodina) more salt-resistant, which means even higher salt levels will be needed to eradicate these organisms."
Can salt really help to fight diseases, such as parasites?
Yes. Salt has been used for decades as a cheap and effective treatment against many diseases, particularly protozoan infections on pond fish such as Chilodonella, Trichodina and Costia, but also some other pathogens, such as gill and skin flukes.
It rarely has an adverse effect on filtration, unlike many other medications, and can either be used as a longer-term low-dose bath or a higher-dose short-term dip.
However, particular care needs to be taken when using strong salt baths, particularly if the fish are already weakened by disease.
Does this work the other way round? Can lowering the salinity in a marine tank eradicate parasites?
Yes, this may work for some marine parasites, but not for all of them, including marine whitespot, contrary to popular belief among those in the marine community!
Dr Peter Burgess, who holds a doctorate on this very subject, told us: "My friend Dr Angelo Colorni in Israel (another Cryptocaryon fanatic, like me!) found that freshwater dips, even long ones, for up to 18 hours, did not prevent development of the parasites in the fish's skin. I guess the skin partly protects the parasites from hypo-salinity effects.
"Colorni found that the free-living infective (theront) stage of Cryptocaryon was hypo-saline sensitive, being killed at salinities below 25 parts per thousand. Of course, most other common skin parasites live on the skin surface, not beneath it, as in ich/crypto, so are more vulnerable to low salinities."
Can salt clear the gills of mucus which builds up when fish suffer from parasites or poisoning?
Yes. According to fish vet Chris Walster, at lower dosages salt can clear the gills of excess mucus.
However, he suspects it may act as an irritant at higher doses: "It could promote mucus production, causing the excess to slough off. This effect probably would be short-term (stress to fish, depletion of mucus cells), and the benefits need to be considered against the disadvantages.
"As such I might use it in an emergency as a one-off treatment where the fish is suffering respiratory distress and no other alternatives were available."
Tetra's Rupert Bridges spoke to their research and development scientists.
He told us: "They suggest that adding salt increases the production of mucus, and therefore speeds the renewal of the mucus layer. The effect is therefore due to a higher turnover of mucus, which helps rid the gills of parasites, etc.
"In my opinion, this is a more satisfactory explanation than any reduction in toxicity of nitrite and ammonia, as salt generally works to rid the blood of excess ammonia and prevent nitrite take-up, not reduce its concentration in the water."
Are fry and young fish more sensitive to salt than adults?
Yes, lab studies have shown that fry are not as tolerant to salt as larger fish. Rothen et al. (2002) studied the effects of salt on the fry of Blue gouramis, Zebra danios, Black widow tetras and Buenos Aires tetras.
All fry tolerated up to 1ppt, and doses as high as 3ppt had little effect on Blue gourami fry. The tetras and danios were OK at 1ppt, but started to suffer at higher dosages. Exercise caution.
What exactly is "tonic salt"? Surely salt is just salt, isn't it?
Tonic, or aquarium salt, is basically plain old sodium chloride, often with a bit of anti-caking agent thrown in to make it easier to pour. Marine salt, on the other hand, is much more complex and contains special blends of minerals, like magnesium and calcium, which are useful for making the water better for marine invertebrates.
Tonic salt doesn't do this. It's designed for therapeutic use, not for making the water resemble that of the sea.
I've been warned off aquarium salts that contain sodium hexocyanoferrate. Why is this?
The additive sodium hexocyanoferrate is an anti-caking agent and is designed to make salt free-flowing. Without an anti-caking agent, salt tends to take up moisture from the air and form hard lumps which are harder to dissolve.
Most fishkeeping writers, myself included, have advised against the use of salt containing this - but I'd bet money on none of them knowing the reason why. I certainly didn't know why this stuff was said to be potentially toxic.
Sodium hexocyanoferrate contains cyanide! Run-off from roadside salt storage facilities, which contain salt containing sodium hexocyanoferrate used for salting icy roads, have been found by Ohno (1990) to contain high levels of cyanide!
Cyanide is toxic to fish at high levels, which is why its use to catch marine fish is frowned upon.
I've been unable to find any evidence in the journals which show that this is harmful to fish in the low levels that are likely to occur in the aquarium. Most suppliers of bulk tonic salt label their product as containing it. The salts are used extensively, and I've never heard of problems relating to their use.
So what's Malawi salt? I thought Malawi was a freshwater lake.
The "salt" recommended for use in Rift Lake cichlid aquaria is probably best called a mineral supplement, since it isn't based on sodium chloride. It's designed to make the water harder and more alkaline, not saltier.
Some people advocate adding tonic salt for Malawis, others reckon it can lead to Malawi Bloat. It is neither an essential nor a recommended addition to a Malawi tank, and we would never advise you to add it.
Malawi Salt, on the other hand, is handy if you live in a softwater area, since it effectively replenishes the missing minerals in your water.
What salt should I use in a brackish aquarium?
Brackish fish expert Dr Neale Monks says: "Marine salt mix. It's so inexpensive in the quantities brackish or freshwater require that there's no point economising with table or rock salt."
How do I calculate the correct dose to add?
Salt is normally dosed in grams per litre or parts per thousand. Both equate to the same amount: 1ppt is 1g per litre. This makes it easy to calculate how much is required if you know the aquarium or pond volume.
Which species are intolerant of salt?
This is a tricky question, because it's hard to confirm that problems seen in fish have been caused by administering salt. I've seen salt used widely on a range of supposedly salt-intolerant species with no obvious ill-effects.
However, many claim that catfishes, especially Corydoras, and Malawi cichlids tolerate salt badly - I've yet to see this myself, though. Research shows that many fish from soft, acidic water will tolerate salt.
Vet Chris Walster told us he had not yet seen a species that appeared intolerant. He said: "Where I have come across an unfamiliar species, I would always recommend a test treatment first. This test should be observed and the fish put into freshwater at the first signs of distress. Salt dosage is varied not only by strength but also by time. Having said that, I am aware that there is variation between species and within species on their tolerance to salt."
Tetra's Rupert Bridges says: "I have come across very few studies that have shown intolerance to salt (NaCl) levels as low as 1-3ppt. One study (Rothen et al. 2002) showed that danio (D. rerio), Gymnocorymbus ternetzi, and Hemigrammus caudovittatus fry displayed higher mortality rates at salinities of 1-3ppt, but that Blue gourami fry were tolerant.
"Often softwater fish are credited with poor salinity tolerance. I have also heard that catfish are cited with poor salinity tolerance, but some species do tolerate reasonably high levels. The general rule would be that salinities up to 3ppt are fine for coldwater fish, but that salt should only be used with caution (perhaps at 0.5-1ppt) or not at all for tropical aquaria."
Dr Peter Burgess also reckons that many catfishes and some other groups can be intolerant: "On an individual basis, freshwater fish that are weakened tend to be less salt-tolerant than healthy individuals."
How does salt affect the toxicity of ammonia to fish?
Ammonia is present in two forms in water: ammonium and free ammonia. Ammonium is not very toxic to fish, but free ammonia is. The ratio of dangerous free ammonia to less toxic ammonium depends on the pH, temperature and salinity. As salinity drops, free ammonia increases.
Importantly, ammonia test kits do not measure the level of free ammonia. Instead, they measure something called total ammonia nitrogen, a combination of free ammonia and ammonium. It is up to you to calculate how much free ammonia is present. The PFK website has a calculator to work this out for you.
Can adding salt reduce the toxicity of nitrite to fish?
Yes, salt reduces the toxicity of nitrite to freshwater fish. Salt is a compound containing sodium and chloride (NaCl). Studies have shown that chloride reduces the toxicity of nitrite to fish, so salt can be added to provide the chloride ions that offer the fish some protection against the nitrite.
Very importantly, the level of chloride required to do this need not be very high at all. Research suggests a dose of between 7:1 and 10:1 chloride to nitrite is all that is needed. So adding salt to protect against nitrite pollution should be safe even for salt-intolerant species, because only a tiny quantity is required. There is a Nitrite Toxicity Calculator on our website to calculate what you need.
Dr Peter Burgess agrees that too many people incorrectly assume that a high level of salt is needed to tackle a nitrite crisis.
Peter told us: "For counteracting the effects of high nitrite, just 100 mg (0.1g) salt per litre is enough. This very low salt level is tolerated by virtually all freshwater fish, even catfishes."
As we went to press, a new paper was published in the journal Environmental Science and Technology which looked at the physiological reason why some fish were more susceptible to nitrite poisoning. Again, it's all down to chloride.
Does salt affect nitrate toxicity?
Yes, there may be some evidence for this. Westin (1974) has shown that nitrate is more toxic in brackish water than in freshwater. New research on nitrate toxicity in freshwater and marine conditions has been published in Chemosphere.
This suggests that the main toxic effect of nitrate is due to its ability to convert oxygen-carrying pigments to forms that are incapable of carrying oxygen. It says that nitrate is technically less toxic in saltier water.
What is the normal therapeutic dose rate?
If fish have parasites, open wounds or osmoregulatory problems that cause dropsy or popeye, a dose between 1-5ppt is the norm, according to fish veterinary texts.
The salt is dissolved in a bucket of water before being added, and then left in the tank as a permanent bath. If you want to sustain the salt level over an extended period, add the same dose of salt to water changes.
Temporary 4-5 minute baths are only used in extreme circumstances. These use a high dose of 30-35ppt, which is about the same as full-strength seawater. Remove the fish if they appear to be getting stressed.
Fish vet Chris Walster says that the dosage required is very variable and should be looked at on a case by case basis: "Salt should not be used as a permanent bath at any dose. Its main use is as a first aid treatment until the correct diagnosis is found, or at low doses in support of other therapies."
He says a general dose of 1.5-3g/l. can be used as a long-term bath for up to two weeks, but that this can be doubled depending on the species and the size of the fish.
He says this is useful after transportation and as a supportive to other therapies, such as when fish are being treated for ulcerations. Smaller and younger fish should be started on doses of 0.5 ppt.
Says Chris: "As a short-term bath, anything up to 37.4ppt per litre with a time of 30 seconds to 10 minutes. This is useful for clearing excess mucus, and by secondary intent, removal and reduction of any pathogens on the surface of the fish."
This is an item from the Practical Fishkeeping website's archives. It may not be reproduced without written permission.
Matt Clarke answers some of the most frequently asked questions on pH.
What is pH?
The pH shows how acidic or alkaline water is, and is a measure of the amount of hydrogen and hydroxyl ions present in the water.
How does the pH scale work?
The pH scale extends from 0 to 14 with 0 being extremely acidic and 14 being extremely alkaline. A pH of 7 is neutral, that is, neither acidic nor alkaline.
The critical thing to remember about the pH scale is that it is logarithmic. This means there is a tenfold difference in each unit. A pH of 8 is 10 times more alkaline than a pH of 7, and a pH of 6 is 10 times more acidic than a pH of 7. So what appear to be small changes in the water chemistry to us are much larger in chemical terms and can have a dramatic effect upon the fish.
How can I measure pH?
You can buy a simple liquid or tablet test kit for 5-10, or a more accurate meter or computer for 50-200.
Test kits come in several forms designed for measuring high range pH (more than 7), low range pH (less than 7) and a broader pH range. Broad range kits are not very accurate and only provide a rough approximation. You can get special kits designed for use in saltwater.
Do some fish need water of a specific pH?
Those from acid waters, like the Amazon and forest pools in West Africa, are called acidophiles and prefer a pH below 7. Fish from alkaline waters, like marines or Malawian or Tanganyikan cichlids, are alkalophiles and prefer a pH over 7, preferably around 8. Both groups are intolerant of the wrong pH.
My tapwater is pH 8. Should I make the water softer and more acidic for my Neons?
While acidophilic fishes prefer soft, acidic conditions, if you live in a hard water area, your shop will probably have acclimatised them to hard, alkaline water. While some shops lower their pH, most keep their community fish in adjusted tapwater.
If you want to keep trickier fishes like Discus, Rams or certain anabantoids, it might be necessary to change the pH and hardness before buying fish. Always ask your retailer about their water when getting new stock for your tank.
If you want to breed fish from softwater areas, you'll need to reduce the pH and hardness to get them to spawn. There may be a link to the chemistry of the water and the number of healthy eggs or fry produced.
What makes pH go down?
The main reason for a drop in pH is carbon dioxide. This gas dissolves in water to form carbonic acid, which gives rise to the hydrogen ions that reduce pH. CO2 is produced by the respiration of plants, bacteria and fish. Other processes can also contribute to a drop in pH, including nitrification, methane fermentation and sulphide oxidation.
This means that if you have lots of fish, lots of plants, or a dirty substrate or clogged undergravel filter, you are most at risk of pH drops. The water that leaves some denitrators can also be very acidic.
What makes pH go up?
Many rocks and gravels sold for use in the tropical freshwater tank contain minerals that increase the pH and hardness. If you don't want the pH to increase, ask your dealer for inert substrates and decor.
Untreated concrete around a pond can increase the pH to dangerous levels, often leading to the loss of fish. Always treat nearby concrete with a pond-sealant paint such as G4.
Photosynthesis can also increase pH. If the tank or pond gets lots of sunlight and contains loads of plants or algae, the pH can get very high in the day.
What is the best way to increase my pH?
If you have soft, acidic tapwater and you wish to keep fish that like hard, alkaline water, the best way to increase the pH and hardness is to use aragonite. This is a calcium-rich mineral and boosts and maintains a high pH and hardness. Unlike coral sand, coral gravel or dolomite chips, aragonite starts to dissolve at a pH of about 7.8 rather than about 8.
Why can't I reduce my pH?
It is difficult to reduce the pH of your water if the KH (carbonate hardness) is too high. The KH provides a buffer to acids and prevents them from decreasing the pH. Some carbonate hardness is important, otherwise the pH will drop as acids are produced in the tank.
Should I add a chemical pH increaser or reducer to the tank to adjust my pH?
Adding liquid or powdered products to increase or decrease pH is rarely a permanent solution. The majority of aquaria have a fairly high KH which provides a buffer to acids, for example.
Adding these products could cause potentially stressful fluctuations in pH. I avoid using them where possible. I would recommend avoiding them unless you really know what effect they are having.
What is the safest way to reduce my pH?
Because a high KH reduces your chances of keeping the pH down, start off with RO water which has a low mineral content. Add a pH-reducing acid, such as API's pH Down, until you reach the desired mark. Replenish hardness with a mineral supplement.
I'm adding CO2 for my plants but it affects my pH. Why?
Carbon dioxide forms carbonic acid when added to water, which reduces the pH. Plants take in CO2 in the day to produce oxygen, but at night the process is reversed. This means that the pH can get very low in the morning and rise during the day. Turn off your CO2 supply at night and add an airstone if the pH drops too low.
What is fishless cycling and why can it be a better technique to use than other methods? Matt Clarke answers some of the most frequently asked questions.
What is fishless cycling?
Fishless cycling is a method of maturing (or cycling) a new biological filter using chemical means rather than adding fish.
Maturation, or cycling, is simply the process of growing beneficial bacteria on the filter. You do this by providing a pollution source for the bacteria to use for energy, and then waiting several weeks for the bacterial colony to reach full size. When all of the bacteria have grown the tank will be free of ammonia and nitrite, nitrate will have started to build up, and the filter is termed mature, or cycled.
Why do you need to mature a new biological filter?
New filters do not contain the bacteria necessary to remove ammonia produced by fish and rotting food, so they are initially unable to keep the water free of pollution. The process is essential to ensure that the filter works correctly by keeping the water free of pollution.
I have been told I can leave my tank empty for a month to mature it. Is this right?
No. It's an old wive's tale. Before the maturation process can start, the bacteria need a source of nutrients. A tank that's left empty, or doesn't get a regular supply of pollution won't mature, and a mature tank that's left empty could potentially "unmature" if there are too few nutrients available for an extended period of time. You need to add a nitrogen source to the tank for the bacteria to use for energy.
My shop has advised me to add fish after a week. What do you say?
There are quite a few different ways to get a new filter going. Historically, fishkeepers have matured a new filter by this technique of stocking slowly with "hardy fish" after the tank has settled for anything from a day to a week.
Practical Fishkeeping has advised against using this technique for many years, and most forums you may visit will probably echo our sentiments. However, quite a lot of retailers still advocate this approach, so your shop may suggest you do it this way.
How does cycling with fish work?
The fish produce ammonia which builds up in the water and encourages the growth of the bacteria. However, as there are very few bacteria present when the filter is new the water will inevitably contain some pollution and this could irritate or harm the fish.
At first ammonia will be a problem, but then after a couple of weeks, nitrite levels will start to peak. The more pollution going in (whether it's from too many fish or too much food) the higher the ammonia and nitrite level will go, and the more likely the fish are to suffer from poisoning.
If you really must mature a new filter in this manner you need to be very patient and very careful. If you add too many fish or feed them too much you'll certainly run into problems. Some fish are hardier than others, so certain species can quickly succumb to disease or die.
If your shop has given you this advice and you've already followed it, test regularly and be prepared to make a drastic water change if conditions become dangerous.
Ideally, you should adopt the more modern fishless cycling technique, which is widely considered more ethical since it does not expose fish to toxins.
What are the benefits of fishless cycling?
Unlike the usual method, fishless cycling allows you to mature the system without placing fish under stress from polluted water. It means you won't have to choose hardy fish that you might not otherwise want to keep. And, if done correctly, it could allow you to reach a higher stocking density quicker and more safely than the conventional method.
Are there any disadvantages?
In most cases you won't be able to put any fish in the tank for at least three or four weeks, sometimes a little longer. Some experiments have shown that tanks cycled using chemicals, rather than organic materials like fish wastes or fish food, may lack all of the required beneficial bacteria and have to undergo a further "maturation" (or time lag) when fish are added.
Is fishless cycling a new technique?
No. The term "fishless cycling" is new but the actual technique has been around since at least the 1970's. One form of fishless cycling, overcompensation, is a widely used technique outside the aquarium hobby, but has only recently started to catch on with fishkeepers.
How do I get started?
Most people opt for an inorganic fishless cycling technique. This basically involves adding a nitrogenous solution, like ammonia, to the tank at regular intervals for the bacteria to break down. Arguably, organic material, such as a piece of fish or some fish food would be the ideal thing to use, since it would also encourage the growth of the heterotrophic bacteria that break down organic matter into ammonia. These might not be present in the same numbers if you cycle inorganically.
Liquid or crystalline forms of ammonia are the most commonly used chemicals for fishless cycling. However, they can be dangerous to handle, and could be tricky to get hold of - chemists and DIY stores sometimes stock ammonia.
We suggest using Waterlife's Biomature. Unlike most other products for cycling new tanks this one contains a source of nitrogen to feed the filter. It's not designed to make the tank mature any quicker, but you could add a bacterial supplement, or ideally some media from a mature filter to give the filter a kick-start.
The food source needs to be added at regular intervals throughout the cycling process.
What happens at first?
If you are cycling organically, by adding a bit of rotting fish, or feeding the empty tank with a pinch of flake food every day, the maturation process will be slightly different to that in a tank that's cycled with chemicals.
The first step (which many fishkeepers are unaware of) is mineralisation. This is the process by which ammonia is formed by heterotrophic bacteria, or by chemical processes (such as deamination) in the tank. Without mineralisation there will be little ammonia for the first bacteria to use. Experiments have shown that this may be why it takes a day or so for the rotting stuff to have an effect on pollution levels, and why the tank won't start to mature straight away.
How is the ammonia broken down?
Initially, the ammonia level will rocket, as there are few bacteria present to break it down. After a few days, autotrophic bacteria called Nitrosomonas start to grow. These nitrifying bacteria break down the nitrogen in the ammonia by oxidising it to nitrite. Nitrite is less harmful, but would still be very dangerous to any fish present. The ammonia level will normally remain very high for a couple of weeks in tropical aquaria, although it could persist for much longer if the water is cold, salty or contains chemicals that affect the bacteria.
What breaks down the nitrite?
The nitrite is broken down by Nitrobacter and Nitrospira bactera into nitrate, which is much less toxic. The most popular method for reducing nitrate is by changing the water. By swapping some of the polluted tank water for dechlorinated tapwater you'll decrease the nitrate level by dilution.
The nitrite level is getting high. When will it go down?
After about a fortnight (depending on the temperature) the nitrite level will have started to peak, and the ammonia level may have started to drop as the Nitrosomonas population has been increasing massively.
Keep testing the pollution levels and you should spot a point when they start to drop (after about week three in most tanks). If there is still some ammonia present, or if the water is cold, the nitrite level may stay for longer. High ammonia inhibits the growth of the Nitrobacter, so the nitrite won't be converted to nitrate until the ammonia level drops a bit lower.
Why is my water cloudy?
The population of bacteria multiplies rapidly during the early stages in order to try and make use of all of the nutrients in the water. Some experiments have shown that there can be as many as 100 million bacteria per gram of filter sand after just a fortnight! Add that up for a whole filter and you're talking squillions.
Over-compensation involves adding much more pollution to the tank than the fish will create when the tank is fully stocked.
Ordinarily, each time fish are added to an aquarium the bacteria need to multiply rapidly to utilise the extra wastes. This can lead to temporary blips, called time lags, where ammonia and nitrite levels are raised for a few days while the bacteria multiply. If you keep sensitive fish, this could stress them. If you exceed the maximum amount of fish the filter can support (the carrying capacity) the "blip" will persist and you will find it virtually impossible to maintain ammonia- and nitrite-free water.
Overcompensating a filter can allow you to stock it with lots of fish in one go. I have used the technique to mature commercial filtration systems so that they are ready to take large shipments of fish in one go. It is also a very useful approach to adopt if you want to stock a mbuna system in one fell swoop.
Can you overdo it?
Yes. Adding too much ammonia will mean that it takes longer for the bacteria break it down. Nitrobacter are inhibited by ammonia. And you could add so much that you exceed the carrying capacity of the filter.
How can I speed up the maturation process?
Controversial research undertaken on many aquarium products for accelerating the speed of maturation have suggested that they are not particularly effective. Some have claimed that they could be based on the wrong types of bacteria. They're still worth a try we reckon and we've had good results with some of them.
The quickest way to boost a new filter is to add mature media from another filter. You need to ensure that the water chemistry is similar for best results.
Why do some tanks take longer to mature than others?
Filter bacteria multiply at different rates depending on the water conditions and the environment within the filter. Some things can repress their growth, while others still allow them to grow but slow their metabolism, making them less effective at oxidising wastes like ammonia and nitrite.
Many fish disease treatments (especially methylene blue, nifurpirinol and antibiotics) will cause problems. Chlorine and chloramine (from raw tapwater) are also things to look out for.
Does temperature matter?
Yes. Temperature is very important. The bacteria grow quicker when the water is warmer (so ponds take longer to mature) and drops in temperature can slow the process. In experiments in marine tanks, a rise of 4C increased ammonia oxidation by 50% and nitrite oxidation by 12%. Dropping the temperature by just 1C reduced ammonia oxidation by 30%.
This item was first published in Practical Fishkeeping in 2002. It was updated in 2010. It may not be reproduced without written permission.
What are T5 lights and are they as good as the hype surrounding them suggests? We've got the answers to some of the most frequently-asked questions.
What are T5 lights?
T5 is simply a collective term for a narrow-diameter fluorescent light tube. Standard 1" fluorescent tubes are sometimes called T8s. T5s run from a special ballast, similar (but different) to the type used for standard fluorescent bulbs.
Why are they better than normal fluorescent tubes?
The makers claim that certain T5s are roughly three to four times more effective than a standard fluorescent bulb of similar wattage. Therefore, they're being marketed as a replacement for the large banks of standard fluorescents used over many reef tanks. By using T5s you'll be able to use fewer tubes than before, and squeeze much more light power under your hood.
Does the light they produce look different?
Yes, T5s produce a "flatter" light, like that produced by a standard fluorescent, rather than an intense directed spot of light like a metal halide. The light levels throughout the tank are more uniform, but you don't get the natural-looking rippling light effect on your substrate you get from a metal halide. Some reefkeepers reckon they lack the "punch" of metal halides for penetrating deep water, so many use a combination of the two types together. Compared to a standard fluorescent, they're considerably brighter to look at.
Are they any good for corals?
They appear to work well in reef tanks and are fast becoming very popular with modern reefers. Experts reckon the light produced may not match that of metal halides but can still be sufficient to get decent coral growth, even in the more demanding SPS corals. The size and coloration of corals from the T5-lit tanks we've seen is very close to that from tanks lit by metal halides.
However, in very deep tanks you might need to confine the light-loving corals towards the upper layers of the tank to ensure they get plenty of light.
Do they have any advantages over metal halides?
Fluorescents like T5s get very warm but the makers claim that they "don't give off radiant heat", so they're less likely to overheat the aquarium than halides. However, they still get almost hot enough to fry an egg on, so they must have more effect upon water temperature than the producers claim. Some can be installed within the hood, so they're handy if space is limited, or if you're unable (or unwilling) to suspend a luminaire from your ceiling.
According to D and D Aquarium Solutions, their T5 bulbs should last for up to 15,000 hours with only a 20% drop off in output. This works out at about 1250 days (more than three years) based on a 12-hour photoperiod. Aquatic Solutions claim 18 months for their "double" tubes. This is far longer than either metal halide or standard fluorescent lamps.
However, as all T5s are still fairly new and we've not seen any long-term data on how long the actual spectrum produced remains useful for corals it might be wise to wait and see on any lifetime claims for T5s.
Virtually all other bulbs eventually deteriorate and we would expect the same to apply to T5s. Indeed, we've heard that some users believe they have already noticed some minor deterioration in their bulbs' output.
How many do I need?
The number and combination of bulbs you add largely depends on what you are keeping. You'll probably be looking at four to six for the average tank, but you might get away with less if you're keeping inverts that are tolerant of lower light levels, such as zoanthids, Pachyclavularia, Leather corals and corallimorphs (mushroom anemones). If you're considering swapping your halides for T5s, D and D Aquarium Solutions reckon you ought to use three 54w T5s to replace each 150w metal halide.
Do they actually work out cheaper than metal halides?
Individually, they're cheaper to buy, but you may need more of them - maybe six or more if the tank is large. Costs can therefore work out similar to metal halides. You could save a few quid on replacement bulbs, though. Some T5 bulbs can be yours for as little as tenner, but you'll be lucky to pick up a metal halide bulb for less than 50 quid.
How do the running costs compare?
By our calculations, based on the recommendations of T5 distributors for the number of bulbs to use, electrical running costs are similar, and potentially slightly higher than with metal halides.
The biggest savings will come to those who currently have a large number of standard fluorescents. T5s kick out more watt-for-watt so you could save a few quid on electricity if you're thinning out the number of bulbs by installing fewer T5s.
What sorts are available?
There are several different designs: stylish luminaire fittings, which include a built-in ballast, reflector and several bulbs, need to be suspended from the ceiling; slimline units, like those from STM and D and D with a ballast and one or two bulbs, are designed to sit under the hood, while canopies like the models from Arcadia and Aquatic Solutions sit on the top of the tank, replacing the hood.
All of those on the market look rather similar. Are there any significant differences?
There are differences in the types of ballast used, which may have some bearing on performance, as well as minor differences in the build quality of the actual light unit itself. However, the most critical differences are in the quality and design of the bulb and reflector used.
There are several different brands of bulb on the market, with each manufacturer making different claims about performance. D and D claim that their bulbs use a superior "A1 phosphor mix" and are the spectra designed specifically for use on aquaria. It's a good idea to use a mixture of bulbs to get the spectrum and light quality you're after. Ask your retailer.
Experts reckon that the gull-wing style of w-shaped reflector is best, because it directs around the tube back to the tank, rather than pointing it back at the bulb.
Can you grow aquatic plants under them?
Yes, there are some bulbs on the market with spectra designed specifically for stimulating plant growth.
This is an item from the Practical Fishkeeping website's archives. It may not be reproduced without written permission.
Some fish prefer soft water, and others benefit from softer water for breeding. But how do you make hard water soft, and how do you interpret hardness levels? Matt Clarke explains.
What is hardness?
Hardness is a term limited to freshwater and describes the total concentration of certain minerals dissolved in the water. Most hardness is largely made up of calcium and magnesium, but other minerals including potassium and sodium contribute to the overall hardness.
Water high in calcium and magnesium is called 'hard' and water deficient in these minerals is called 'soft'. In parts of Wales, Yorkshire, Scotland and Cornwall, the tapwater can be quite soft, but, in most areas of the UK water is very hard and alkaline.
Conductivity, which you can measure with a special electronic meter, is a measure of the overall mineral content of the water, not the concentration of specific minerals.
Why is this important?
The water in different geographic regions and habitats differs in its hardness and pH. Fish have evolved to live in the chemical conditions of their natural environment, so they have preferences or needs for water of a specific chemistry in captivity.
Hardness is most commonly affected by the surrounding geology of the area. In places where rocks are calcareous (calcium-rich), like Lake Tanganyika, the water is very hard; where the rocks are inert (have no effect on water chemistry) the water can be neutral or soft.
Fish from areas where the water is roughly neutral are fairly adaptable and will tolerate most conditions, providing they're not too extreme - but fish from very soft, acidic water (acidophiles), or very hard alkaline water (alkalophiles) won't tolerate conditions at the other end of the scale. So it's a bad idea to keep Discus (acidophiles) in very hard water, or Tanganyikan cichlids (alkalophiles) in very soft conditions.
Some species are reluctant to breed in water of the wrong hardness. Water hardness may also have some effect on the hatch rate of fish eggs.
Are pH and hardness linked?
Not exactly, but sort of. The pH is a measure of the amount of hydroxyl and hydrogen present in the water, while hardness is a measure of the amount of certain minerals. However, soft water is usually also acidic (low pH) and hard water is usually alkaline (high pH).
These properties are reflected in the water chemistry requirements of the fish. If you're adjusting the hardness or pH to suit fish with specialist needs, remember that not all strategies for reducing the hardness will lower the pH, and some techniques for lowering pH will have no effect on hardness.
How is the hardness of water expressed?
This is where things get confusing, because there are several ways of expressing water hardness. Different books, test kit manufacturers and fishkeeping experts use different measures.
It's a grey area - most of the industry experts we spoke to admitted some confusion.
Measures of hardness
GH - General, total or permanent hardness is a measure of the overall concentration of calcium, magnesium and other ions. It's measured in degrees, with one degree equal to about 17.9mg/l. The degree symbol is often replaced with a "d" (i.e. 6dGH). The harder the water, the higher the GH.
KH - Buffering capacity, temporary or carbonate hardness. The 'K' in KH comes from the German word 'karbonate'. KH is a measure of bicarbonate and carbonate ions that act as buffers to prevent the pH dropping. The ions that make up KH can be removed by boiling.
KH makes up a component of GH, so boiling will also reduceGH slightly. One degree KH is equal to 17.9 mg/I CaCO3. It's also measured in degrees. The degree symbol may be replaced with a d (ie. 2 dKH). Because KH makes up part of the GH value, you can't have a KH higher than your GH level.
DH - Deutsche harte or German hardness (sometimes written as dH) is (according to our consensus of experts) essentially the same as GH. (But some experts debate this). It's sometimes used in Discus keeping circles. It's also measured in degrees One degree DH is equal to 17.9 mg/I CaCO3.
Clark - English degrees of hardness are actually rarely used in the UK. One degree Clark is equal to 14.3 mg/I CaCO3.
Some argue that, because Clark is the form of hardness we're supposed to use in the UK, that this means that when we say GH, we're actually talking about 14.3 mg/l CaCO3 rather than the 17.9 mg/l CaCO3 you'd see if we were using dH. A fair point, but I've yet to meet anyone, inside or outside fishkeeping who actually uses Clark. Everyone considers GH in England to be 17.9 mg/l CaCO3 so it's essentially the same as DH in practice.
Hardness - American degrees of hardness. One degree is equal to 1 mg/I.
If there are so many, which one should I use?
At PFK, we generally use GH and KH, because they're the most descriptive terms. It might be easier if everyone stuck to the same measure, like mg/litre CaCO3, but unlike GH and KH, there are few mentions of CaCO3 values in fishkeeping literature.
How do I test for hardness?
There are two main types of test kit on the market for measuring hardness: GH kits and KH kits.
Hardness kits are based on titration, so you add the reagent drop by drop until the colour changes. The first drop may make the sample go blue and you then add more reagent one drop at a time, counting until the sample starts to change colour. The final drop will make the sample change to a different colour (usually red or orange). Simply add up the number of drops to get the hardness.
Good test kits come with some general information on the right hardness levels for different fish and a conversion chart that you use to translate the result into a different measure of hardness, for example, DH to Clark.
What hardness do different fish species need?
Most species are OK in moderately hard or slightly soft water. Acidophiles and alkalophiles are less tolerant, You probably won't need to make large or exact adjustments if you're keeping general community fish, but if you want to breed some species, you may need to soften and acidity your water. Check in a good book.
What about Discus?
Discus will not breed as successfully or as vigorously in hard, alkaline water. For general Discus keeping a pH of 6.0-7.0, adequate. But, for breeding, soften and acidity the water a little more. A pH of 6.0-6.5, GH 2 and KH 1 is better - but you will need to make sure you make lots of water changes to prevent the pH from crashing.
What's the best way to make my water soft?
While there are some resins on the market that remove certain minerals from the water, the easiest method is to use demineralised water, like RO from a reverse osmosis unit. Rain water carries a risk of pollution and may be very acidic. Make sure you collect from a clean roof and filter it through activated carbon.
What is a reverse osmosis unit?
A reverse osmosis (RO) unit is a tapwater purification unit which produces demineralised (hardness-free) water with a very low pollutant content.
The pH is usually neutral, and the GH and KH are usually 0. This lack of buffering capacity means that you can easily reduce the pH to the desired level by adding peat or acids, and you can adjust the hardness by adding minerals.
You must never use raw RO water. Fish need some minerals in the water for physiochemical reasons. Similarly, if there's no KH to buffer acids in the fish wastes, or from photosynthesis and the respiration of fish and plants, the pH will fluctuate wildly or drop to a dangerous level.
You can remineralise RO water by adding a compound like Tropic Mann Re-Mineral F or API Electro-Right. RO units need plumbing in to the mains water system, and most models generally need to be run continuously. But you can also buy RO water from most good shops.
What does peat do?
Peat is thought to take in certain minerals and release chemicals including tannic and humic acids into the water which acidity it, if, and only if, the water has a low enough KH. Peat can be effective, but won't do much if you've got hard, alkaline water because the KH can prevent the acids from reducing the pH. Peat filtering the water is said to be most effective...
Can I use water from my tapwater softener?
No - most tapwater softeners work by swapping calcium and magnesium for sodium. The water is soft, as the calcium and magnesium have been removed, but it contains too much sodium to be used safely with fish.
How do I make water of the required hardness?
There is a mathematical way to do this using something called Pearson's Square, but some mental arithmetic and trial and error is just as effective. RO is the best stuff to use. Add small, measured quantities of re-mineralising compound to one litre volume of hardness-free water until you reach the hardness you're after. Then simply scale up the dosage to treat a bucket - the results should be the same.
I can't reduce my pH and hardness. What might be the cause?
Chances are, the decor is leaching chemicals into the water that influence the pH and hardness.
Many aquarium gravels, and many types of rock, are calcareous and will make the KH (and therefore the GH) higher, and usually also influence the pH. This means that if you do manage to reduce the pH or hardness by using RO, rain water, chemicals or resins, it probably won't stay down for long. If you keep soft, acid water fish and you want to prevent the hardness and pH from rising, use an inert substrate like aquarium sand or lime-free gravel.
Adding pH-reducing acids, or bases to boost the pH can cause more harm than good. Fish are intolerant of large swings in the pH and may fall ill or die if you make big changes to the water chemistry. For the majority of species, it's not necessary to alter the pH, so it's safest not to meddle.
This is an article from the Practical Fishkeeping website's archives. It may not be reproduced without written permission.
Matt Clarke answers some of the most frequently asked questions on livebearers...
What are livebearers?
Most fish lay eggs, but some give birth to live young. There are two different types of livebearers - viviparous and ovoviviparous. In ovoviviparous fishes the eggs hatch internally and are born fully-formed, receiving nutrition from the egg yolk. In viviparous fishes the fry recieve nourishment from the mother.
About 15 of the approximately 480 fish families known exhibit some form of livebearing. This includes half of all sharks and rays, as well as the livebearing tooth-carps, such as Guppies, Platies, Mollies and Swordtails, and a number of unusual species.
How do I sex livebearers?
Male livebearers, like Guppies, Platies, Mollies and Swordtails, have a modified anal fin called a gonopodium, which is used to internally fertilise the female. Females lack gonopodia and have a triangular anal fin instead, so they're easily sexed.
In some species, such as Phallichthys fairweatheri, the gonopodium may be as much as 50% of the total body length.
Hormone treated female Guppies may have gonopodia. These are useless for breeding and should be avoided.
Are they best kept in pairs?
Male livebearers can be somewhat over-amorous, so it's less stressful for the females to keep at least two females per male, rather than just a pair.
How long is the gestation period?
It varies according to species, but most common livebearing tooth-carps can give birth to between 20-200 fry every 4-6 weeks.
Most livebearers reach sexual maturity quickly. Male Guppies can breed after two months; females at three months. So the tank can soon become overpopulated if you have lots of females.
I keep getting fry, but there are no males in my tank. How can this be possible?
Many livebearers produce packets of sperm called spermatozeugmata and impregnate the female with these. Spermatozeugmata can remain in the folds of the ovaries and uterus of female livebearers for up to a year in some species, allowing the female to fertilise several successive batches of eggs from a single spawning.
Chances are, if you buy female livebearers, that they've already been impregnated by any males in the tank, so even if you buy all females you still may become overrun with fry. If you don't want fry, don't keep females.
How do I feed the fry?
Livebearer fry are usually larger than the fry of egg laying species, and are normally able to take fine foods straight away, unlike the fry of egg layers which need to absorb the yolk sac before they will eat. Most newborn fry will take liquid or powdered fry foods for livebearers, or live or frozen brine shrimp nauplii. They grow quickly and within a couple of weeks can be weaned on to crumbled flake or growth foods.
Should I use a breeding trap?
Most experts agree that breeding traps aren't ideal for livebearers and that they may cause gravid (pregnant) females undue stress.
You can raise a reasonable number of fry in a community tank if you plant heavily with bushy plants like Cabomba, and ensure there are no fish present large enough to eat the fry. For bigger broods you'll need a separate tank.
I've been told that Guppies are easy to keep. Why do mine always die?
A decade or two ago, Guppies were tough, disease-resistant and easy to keep. Today, things are quite different and they can be hard to keep, disease-prone and sensitive to pollution. Some shops won't stock them any more, and very few recommend them to new fishkeepers.
It's likely that continued inbreeding, the use of hormones and incorrect use of antibiotics have caused genetic and health problems, making many strains much weaker.
The fins of my Guppies keep getting shredded. What's wrong?
Male Guppies have long fins that may be nipped by other fish, particularly by some barbs and tetras. Check the compatibility of any fish before buying them.
While fin-nipping is common, shredded fins are sometimes a sign of Guppy disease, which is thought to be caused by the ciliate parasite Tetrahymena.
Treatment is often difficult, but anti-parasite treatments, especially those containing some copper, can be be effective.
Adding aquarium salt at a dose of 2-3 g/litre can help reduce salt loss through the open wounds. Good water quality is vital.
Nitrate is less of a problem in your aquarium than ammonia or nitrite, but it still shouldn't be ignored. Matt Clarke answers some of the most frequently asked questions on nitrate.
What is nitrate?
Nitrate (NO3 ) is a by-product of the breakdown of fish wastes by beneficial bacteria living in the filter. It encourages algal growth and may be toxic to some fish and invertebrates.
How can I tell how much is present in the tank?
You should test your water every week for signs of nitrate using a liquid or tablet test kit. Test your tapwater at the same time and compare the two.
If you are maintaining your tank properly, the two nitrate levels should be quite similar. If you're not, the nitrate level in your tank will be much higher.
Surely nitrate hasn't always been seen as a problem?
There's been a sneaking suspicion that high levels can cause problems for fish for many years. Research has failed to show that it is toxic to most species, except at high levels. However, fishkeeping experience suggests that it does actually cause a number of problems for fish.
What levels should I be aiming for?
Try to keep the nitrate level as low as possible. Some fish and inverts are particularly sensitive to raised levels. For inverts and sensitive marines, the levels must be below 15ppm. Tropical freshwater species should be kept below 40ppm, where possible.
How do I maintain a low nitrate level?
Overfeeding is a common cause of high nitrate levels. Regular partial water changes of 25% every week or two help to keep the nitrate level low. Do them with a syphon-powered gravel cleaner and remove decaying organic material from the gravel at the same time.
Nitrate-removing filter media will keep the nitrate level extra low, but isn't a substitute for plenty of water changes.
What effect will high nitrate levels have on my fish?
High levels of nitrate will stress your fish. This affects their immune systems and they are much more at risk from diseases such as whitespot.
Increased levels over a long term may reduce your fishes' lifespans, cause deformities and won't help much if you're trying to breed them - poor water quality doesn't put fish in the mood.
What should I do if the nitrate level in my tapwater is very high?
If you're keeping delicate fish or inverts any water you use for water changes should be run through a nitrate-removing resin, or a tapwater filter like a Nitragon, before use to remove the nitrate.
An RO unit is even better as it also filters out metals, pesticides, hardness etc, so it's ideal for softwater fish as well as delicate marine species.
The existing fish in my aquarium all seem healthy and my ammonia and nitrite levels are at nil. The tank has been set up for two years. Every time I buy new fish, they stop eating after a couple of days and then, usually within a week, they die. What's the problem?
You may have checked the ammonia and nitrite levels (which are very important), but what about your nitrate level?
If your nitrate has gradually risen over time since your tank was set up, your fish will probably have built up some resistance to it. But any new stock you add to a tank where there is a high nitrate level may fall ill or die.
Try to stay on top of tank maintenance and check how much you're feeding your fish. Remember to remove all uneaten food from the aquarium.
Nitrite is a toxic pollutant and high levels can be deadly for your fish. Matt Clarke explains what causes nitrite to rise, and what you can do to save your fish in a water quality crisis...
What is nitrite?
Nitrite (NO2) is a highly toxic pollutant which is produced by bacteria during the breakdown of fish wastes and other organic materials through a process called nitrification.
Beneficial filter bacteria called Nitrosomonas, oxidise deadly ammonia (NH4) from decomposing materials and fish wastes to nitrite, which is slightly less toxic to fish. Other bacteria, like Nitrospira and Nitrobacter, then convert the nitrite to nitrate (NO3), which is only mildly toxic by comparison. It's very important to test your water regularly for signs of ammonia, nitrite and nitrate.
Why does nitrite build up?
High nitrite levels arise because there's too much pollution being produced for the beneficial bacteria to cope with.
Filter bacteria are present in proportion to the amount of pollution entering the tank and take time to grow to levels where they can handle all of the pollution being produced by the fish.
While they're building-up their numbers in an attempt to consume all of the food available to them, the water will be polluted with ammonia and nitrite, which is stressful to the fish. When there are plenty of bacteria and a constant amount of waste gets added each day, the ammonia and nitrite level should stay at zero.
What causes high nitrite?
Overfeeding and overstocking can lead to high nitrite levels, but incorrect filter maintenance and new tank syndrome are perhaps the most common cause.
New filters (and media which has been washed in tapwater or replaced with new) contain few bacteria and aren't capable of removing much pollution. It generally takes the bacteria 4-6 weeks to build-up, or mature, depending on the temperature and chemistry of the water.
Only wash filter media in old tank water, not under the tap, and always replace media bit by bit, not all at the same time.
To speed-up the growth of bacteria in new filters you can transfer some media from an existing filter, or add a bacterial starter culture and food source.
If you've got a new tank, or filter, don't add too many fish, and don't add much food. The more pollution entering the tank the more dangerous the conditions will become for any fish present.
How does it harm the fish?
Nitrite enters the blood of the fish at the gills and can harm the fish in a number of different ways.
Most notably it oxidises the iron in their haemoglobin to produce a molecule called methaemoglobin, which unlike haemoglobin, can't carry oxygen around the blood. This process (called methaemoglobinemia) sometimes turns the blood brown and causes extreme breathing difficulty or even suffocation.
Nitrite also builds up in the blood causing poisoning, and may lead to liver, gill and blood cell damage.
Exposure to nitrite for long periods makes the immune system less effective and the fish may start to suffer from diseases, such as white spot and bacterial infections, like fin rot or ulcers, if they haven't already died from nitrite poisoning.
What symptoms might the fish show?
Due to the problems they experience in breathing normally, affected fish often gasp or hang at the surface where the oxygen content of the water is at its greatest. They'll usually move their gills more quickly, and may hold their fins close to their body. Although fish may show some signs of nitrite poisoning, you can't tell how much is present unless you test the water.
Is it toxic to all fish?
Different species of fish, and even different individuals of the same species, may have different tolerances to nitrite. Some species can reduce the rate at which it enters the blood through the gills, and it's toxicity is also affected by water chemistry. Therefore, not all of the fish in the tank or pond will fall ill or die as a result of a raised nitrite level.
What level should I aim for?
The nitrite level should always be zero, or as close to zero as you can get it. Under certain conditions, even relatively low nitrite levels of 0.25 mg/l may be enough to weaken sensitive species. Anything above 0.1 mg/l should be viewed as unacceptable and a potential cause of stress, although some fish might tolerate very high levels.
Check the form the nitrite result is given as. Some results need converting from nitrite-nitrogen.
What should I do if I detect nitrite?
Your first course of action upon finding nitrite should be to find out why the level is high and try to ensure that whatever caused it never happens again. Then, make a large (50% or more) partial water change to dilute the concentration of nitrite in the water.
Test daily and be prepared to make further water changes to reduce the levels.
Losses are always higher when the dissolved oxygen levels are lower, so boost the dissolved oxygen levels by adding an airstone, or by using a venturi. Keep a close eye on the fish to see if they develop any diseases.
What can I add to make nitrite less toxic to the fish?
Aquarium salt (sodium chloride) has long been used as an aid to reducing the toxicity of nitrite, because it has been shown to prevent methaemoglobinemia under certain conditions.
Some fishkeepers don't like using salt, but in my experience, when used at the correct dosage, it's never caused problems for any fish, even stereotypically salt-intolerant species. A fairly low level of salt can have a significant effect on reducing the toxicity of nitrite, so you don't need to add very much.
Research suggests a 10:1 dose (just 10mg/l of salt per 1mg/l nitrite) is effective for most freshwater species. The addition of salt for controlling disease or osmoregulatory problems does need higher doses!
Why does adding salt help?
The addition of salt provides chloride which reduces both the methaemoglobinemia and the toxicity of nitrite in the blood. However, interestingly, although the chloride has always been provided via sodium chloride, more recent research suggests that calcium chloride can work as well, if not better, because the additional calcium is also thought to decrease gill permeability, which prevents as much nitrite entering the blood.
For this reason, fishes kept in water with a higher calcium and chloride level, are usually less sensitive to nitrite than those in freshwater with a low chloride and calcium concentration - but many marines remain sensitive.
Theoretically, fish kept in warm, soft water (ie. Discus) are most at risk, but nitrite can and does kill fish in all water conditions.