I am hoping to get some Checkerboard cichlids for my 200 l aquarium. It has a length of 100cm, a temperature of 27.5°C and an oversized filter. The substrate is silver sand, and it’s heavily planted, with bogwood and branches and a few rocks, leaf litter and Savu pods. The pH is 6.8–7 — I use tapwater, but there are peat granules in the filter. Water changes are carried out every two weeks, meaning nitrate and nitrite is always low. Lighting is quite dim, but there are floating plants.
The tank holds two Vaillant’s gouramis, six Congo tetras, eight Cardinal tetras, an L168 butterfly pleco, eight mixed corys, eight Shadow catfish, six Bentosi tetras and some Amano shrimp.
If Checkerboard cichlids are suitable, would you recommend a pair or harem?
SAM PUTNAM, EMAIL
That sounds like a great set-up for Checkerboard cichlids! There are two species — Dicrossus maculatus with the heavier checkerboard pattern on its body and shorter fins, and D. filamentosus, with that beautiful lyretail. D. maculatus are the cheaper of the two and usually come in wild caught, while D. filamentosus commands a premium and is
bred in the Czech Republic by suppliers
Both will come in small and not looking like they do in the pictures, but give them the right conditions, like it sounds like you have in your tank, and they will thrive.
Juveniles will not be easy to sex so start with a group, with the aim of eventually obtaining a pair. Juveniles do shoal in the wild so will get on fine, but once those males hit 5cm and start to colour up they will want a space all of their own, and I would only look to keep an adult pair in a tank of your size long term.
I recently set up a planted Fluval Edge 23 l/5 gal tank, after a few weeks and some new occupants later I noticed this ‘creature’, which I’ve since discovered could be an aquatic slime mold — but that’s where the info ends unless you understand scientific talk.
It seems to move around the tank, along the wood, occasionally disappearing into the substrate. Whilst I never see movement, if left for a period of time it will have relocated to another part of the tank.
For now, I’ve manually removed it with a syphon and toothbrush. But where did it come from and how do I stop it coming back?
LUKE GLOVER, EMAIL
Slime molds — those that are big enough to see, at least — are uncommon in aquaria, though small colonies could easily go unnoticed, so it’s hard to say whether or not they’re a normal part of freshwater set-ups.
What we can say is that they’re a bit like fungi in habits, consuming organic matter such as decaying plant material. That being the case, they’re not likely to threaten your fish directly. but just like fungi, they are a sign that’s something amiss with the aquarium. If you can see slime molds or tufts of fungi, there’s something in the tank decaying that they’re digesting. In doing so they’re producing waste products that the filter has to deal with, ultimately raising nitrate levels between water changes.
The fact that your tank is very small highlights some possibilities. A deep substrate can be very good at accumulating debris that the slime mold could be feeding on. It’s also very easy to overstock a small aquarium or overfeed the tank residents, and the faeces and uneaten food will provide food for your slime mold.
The one time I’ve dealt with slime molds in an aquarium was after adding fresh wood as decoration, as opposed to cured bogwood. Again, organic material in the wood provided food for the slime molds.
A lack of water circulation can also prevent organic debris from ending up in the filter where it can be processed by the bacteria, providing more food for the slime mold.
I've learnt the hard way that you really can't afford to skimp on quarantining new fish!
I have a heavily planted 120 l tank with around 15 Amano and Red cherry shrimp, five false Julie corys and one surviving Fork tailed blue eye. The blue eye was once one of eight along with two elderly but much loved guppies — until I was foolish enough to add a few more blue eyes straight into the tank.
Fairly early on it seemed that two of the new fish weren't happy and seemed to not be eating. Then came a period of regularly dead fish and much desperate searching for cause and diagnose.
Eventually we realised we had Camallanus worms. Treatment seems to be a nightmare and the Internet is full of confusion, with lots of sites recommending treatments that don't seem to be available in the UK or advising bird dewormers which I'm hesitant about.
I understand the dewormer would kill my shrimp and some sources seem to say corys might struggle too. Should I move the shrimp and risk the corys (they don't seem to have any signs of infection)? Can the shrimp carry the infestation and re infect the tank? Is there a different medicine I should be using?
JENNY MARCHANT, EMAIL
You don’t mention how you arrived at your diagnosis of Camallanus. Diagnosis requires the observation of one or more red-brown worms (up to 2cm/0.8in long) protruding from the fish’s vent, or the discovery of the worms within the gut of a dead fish.
Assuming you have observed the actual worms, then we need to consider a few points about Camallanus infections: there are several species of Camallanus and they infest various freshwater fishes, including guppies. Living within the fish’s gut, these worms remain out of sight — so you may not have detected them even if you had quarantined your new fish (although quarantine is always a good idea). Generally, it is only when one or more female worms protrude from the fish’s vent to shed their larvae that a Camallanus problem is discovered. Low numbers of worms in the gut may cause no obvious disease signs but heavy infestations can lead to body wastage and can be fatal.
Fish acquire Camallanus through eating worm-infested copepods (tiny crustacean relatives of water-fleas, sometimes sold as live food). In the case of Camallanus cotti (which infests guppies, Betta, and other species), some experts believe that fish can additionally pick up this worm directly, by ingesting free-living worm larvae in the water. There is no evidence, to my knowledge, that shrimps will harbour Camallanus.
As for treatment — and this assumes you have a confirmed diagnosis of Camallanus — I would choose one of the commercial fish wormers that contains either Flubendazole or Fenbendazole as the active ingredient. These wormers are reportedly toxic to shrimps so you will, unfortunately, have to treat all your fish (including the corys) in an isolation tank — I suggest isolating them for four weeks. You may need to re-dose every week or so during this isolation period — but follow the manufacturer’s instructions.
DR PETER BURGESS
I am new to fishkeeping and I recently tried a food claimed to feed fish at different levels in the aquarium. When I added it most of it went straight down to the bottom of the tank due to the flow of the water. Is there a way to stop it sinking so quickly? Is it better if I turn my filter off when I feed the fish?
G. REES, EMAIL
It really depends on what type of filter you have and how you position it.
Most internal filters return water to the tank horizontally, which should produce a flow across the tank, (and often weakly back again toward the filter as the flow deflects off the opposite side). This should mean that any sinking food added will remain suspended in the water column for a short time as it sinks.
External filters generally have a similar effect but are more adjustable, so it is possible to position the return pipe or spray bar to send the water straight down to the tank floor, and this would rapidly wash any food down with it.
Some tanks have filters that are situated in the hood and work by gravity with the water dropping through them and then back into the tank; these can make a fierce downward flow as well. If your filter is pushing water downwards then it can be a good idea to switch the filter off during feeding to prevent this — just be sure to switch it on again afterwards!
Many fish foods have a mixture of densities in the one pack, so some will float, some sink rapidly and some slowly. In theory this should offer most types of fish a chance to feed. It might also be worth considering feeding in smaller quantities so the fish can gobble up most of the food before it reaches the bottom.
Of course any bottom feeding species such as Corydoras will appreciate the food that sinks to the substrate.
I have a healthy male Dwarf gourami but I have lost three females, all of which have wasted away. He doesn’t seem to be bullying them — they just seem to become skinny, stop eating and then hang about in one corner of the tank. I’m not inclined to try another, so will he be OK on his own — or should these fish really have a mate?
LYNN WOODS, EMAIL
Dwarf gouramis are an old aquarium favourite, and rightly so given the lovely colour displayed by the males. Native to India, Pakistan and Bangladesh, the fish seen in the hobby are largely commercially produced in Singapore. Sadly many of these fish are plagued by a nasty disease known as ‘Dwarf gourami iridovirus’, some of the symptoms of which are similar to those you describe seeing in the females you have lost. This disease is untreatable, but the fact that the male is unaffected could be down to a natural immunity.
However, the males of this species are also well known for bullying and pestering females, especially if the tank is too small or doesn’t offer enough cover in the form of dense vegetation.
Lush floating plants are ideal for this, allowing females to hide away from the male’s unwanted attentions. As you have already lost three females it seems to me that even though you haven’t noticed any bullying it is still the most likely cause of their demise. A well-established healthy male will see each new female as a potential mate and immediately begin trying to impress her, regardless of her condition.
This probably means the new fish have no time to settle in and feed up and simply fade away.
My advice is to keep the male by himself. He won’t suffer from being kept alone and you’ll be able to enjoy his gorgeous colouration without worrying about a harassed and sickly female.