Hang out with the cool crowd

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Your tanks: Mark Allison
30 October 2019
Many of the fish we see swimming energetically in the ‘tropical’ section of our local fish shop are from countries with climates that while perhaps not as varied in temperature as our own island nation.

You can have colourful aquarium fish without having to turn the thermostat up to ‘tropical’ — and the choice is wider than you think...

WORDS: BOB MEHEN

When people think of colourful coldwater fish, the ones that usually spring to mind are fancy goldfish — all eyes, pot bellies and diaphanous flowing fins in bright orange and red.

The fact is though that many of the fish we see swimming energetically in the ‘tropical’ section of our local fish shop are from countries with climates that while perhaps not as varied in temperature as our own island nation, nevertheless still swing high and low with the seasons.

These fish are best described as ‘temperate’ rather than ‘coldwater’, as year round chill will not be to their liking, but if you live in the average, centrally heated UK house then they should thrive, providing plenty of colour without the expense of having a heater constantly operating.

Some more switched on stores have been quick to cotton on to this trend and already have a temperate section filled with some of the hardy regulars often associated with tropical tanks but perfectly suited to cooler climes. The once ubiquitous goldfish, fat fancies aside, have increasingly been shuffled out into the pond section, where they can thrive and grow to their full potential, to be replaced by the aquarium friendly faces of White Cloud Mountain minnows, Zebra danios and Variatus platies to name a few.

Beyond zebras

We probably all know the amazing toughness and adaptability displayed by that mainstay of the hobby, the Zebra danio, Danio rerio. It’s no surprise these hardy little fish are one of those species regularly recommended to beginners or plonked into new, biologically dead aquaria in the unnecessary practice of ‘fish-in cycling’ — they are tough, adaptable and while not strikingly colourful, offer pattern and movement.

What many people don’t realise is that some of their close cousins have many of the same characteristics, but wrapped up in a more vibrant livery.

 Orange-finned danio,  Brachydanio kyathit

Orange-finned danio,  Brachydanio kyathit

Boasting the same pinstripe perfection of its Zebra brethren, Brachydanio kyathit lives up to its common name of Orange-finned danio, with its black barred body set off wonderfully by deep, burnt orange fins, with the same rich colouration spilling over onto their bodies in prime specimens. Like the classic Zebra danio, a spotted form is also often available.

Scientific name: Brachydanio kyathit (Brak-ee-dan-ee-oh kee-ah-thit).
Size: 4cm/1.5in.
Origin: Myanmar.
Water chemistry: pH 6.5 to 7.5. Soft to moderately soft water.
Temperature: 16–26°C/60–78°F.
Minimum tank size: 80 l/17 gal with a footprint of 90 x 30cm/36 x 12in.

 Pearl danio,  Brachydanio albolineata

Pearl danio, Brachydanio albolineata

One fish most of us will see regularly, but perhaps not be aware of its temperate potential is the Pearl danio, Brachydanio albolineata. These glossy little fish are exquisite, changing colour like a film of oil on a puddle as their flanks hit the light, moving from metallic blue, then green, violet, pink and gold. In dull conditions they look like a washed out danio version of a Glowlight tetra but given good food, water and lighting they truly shine.

Scientific name: Brachydanio albolineata (Brak-ee-dan-ee-oh al-bow-lin-ee-ah-ta).
Size: 5cm/2in.
Origin: Widely distributed across south-eastern Asia.
Water chemistry: pH 6 to 8. Soft to hard water.
Temperature: 16–25°C/60–77°F.
Minimum tank size: 80 l/17 gal with a footprint of 90 x 30cm/36 x 12in.

 Glowlight danio,  Celestichthys choprae

Glowlight danio, Celestichthys choprae

Arguably even more delightful is the diminutive Glowlight danio, Celestichthys choprae. Like the Pearl, these fish shine and glitter under suitable lighting, with their gold edged fins a real stand out feature. Again their colour changes depending on the light, but the typically warm, pinkish orange hue of the fish’s body is contrasted by a series of blue-black vertical bars.

Scientific name: Celestichthys choprae (Sell-ess-tick-thiss chop-ray).
Size: 3cm/1.2in.
Origin: Northern Myanmar.
Water chemistry: pH 6 to 7.5. Soft to slightly hard water.
Temperature: 16–26°C/60–78°F.
Minimum tank size: 65 l/14 gal with a footprint of 75 x 30cm/30 x 12in.

 Gold ring danio,  Brachydanio tinwini.

Gold ring danio, Brachydanio tinwini.

The Gold ring danio, Brachydanio tinwini, is perhaps the most boldly marked of the ‘danios’ with a series of black spots covering their body and fins, surrounded by a metallic golden sheen, all contained in a small tank friendly adult size of around 2.5cm/1in.

Scientific name: Brachydanio tinwini (Brak-ee-dan-ee-oh tin-win-ee).
Size: 2.5cm/1in.
Origin: Northern Myanmar.
Water chemistry: pH 6.5 to 7.5. Soft to moderately soft water.
Temperature: 18–26°C/64–78°F.
Minimum tank size: 40 l/9 gal with a footprint of 45 x 30cm/18 x 12in.

 Bengal danio,  Devario devario

Bengal danio, Devario devario

Those with bigger tanks wanting some real action may be tempted by one of the wonderful species of Barilius, Indian hill trout, occasionally offered for sale. However these are fish with a large adult size, pugnacious nature and surprisingly capacious mouths, best left for larger, specialist tanks with torrent like flow. Consider instead the ‘budget Barilius’ — the Bengal danio, Devario devario. They share the same restless energy and twitchy, active nature of the smaller ‘danios’ and with sufficient space a swirling shoal of these deeper-bodied fish can make a striking display, with their metallic green-blue flanks marked with warm golden blotches. They reach around 7.5cm/3in.

Scientific name: Devario devario (Dev-arr-ee-oh dev-arr-ee-oh).
Size: 7.5cm/3in.
Origin: Northern India, Nepal and Bangladesh.
Water chemistry: pH 6 to 8. Soft to moderately hard water.
Temperature: 15–26°C/59–78°F.
Minimum tank size: 160 l/35 gal with a footprint of 120 x45cm/48 x 18in. 

Temperate tetras

In many tropical tanks tetras rule the roost when it comes to midwater dwelling, shoaling, colourful fish. Mainstays like Neons, Cardinals, Glowlights and Lemons pack aquatic shop tanks with colour. Sadly these are all true ‘tropicals’, which like to bask in the mid 20s°C and will soon look off colour if allowed to dip much below this for long.

 Buenos Aires tetra,  Hyphessobrycon anisitsi

Buenos Aires tetra, Hyphessobrycon anisitsi

There are however a couple of fish shop staple tetras that aren’t adverse to a cool shower, coming as they do from regions of South America where the climate isn’t wall to wall sunshine. Most commonly seen is the stout Buenos Aires tetra, Hyphessobrycon anisitsi. The temperature of these fish’s natural habitat varies considerably and if kept constantly at the high end of their tolerance in aquaria they can live considerably shortened lives at constant fast-forward. Deep bodied and reaching around 6cm/2.5in they sport attractive orange/red fins that set off their overall greenish blue body colouration nicely and the caudal peduncle is marked with a bold black blotch. An albino form is also available which retains the fin colouration but loses all the other colours and markings as a result. They can be ‘nippy’ so choose tank mates with care. Stocking them in groups of ten or more often redistributes these anti-social tendencies amongst their own kind to the degree it is no longer an issue.

Scientific name: Hyphessobrycon anisitsi (High-fess-oh-bry-con an-iss-it-see).
Size: 6cm/2.5in.
Origin: Brazil, Paraguay, Argentina and Uruguay.
Water chemistry: pH 5.5 to 8.5. Soft to hard water.
Temperature: 16–28°C/60–82°F.
Minimum tank size: 80 l/17 gal with a footprint of 90 x 30cm/36 x 12in.

 Bloodfin tetra,  Aphyocharax anisitsi

Bloodfin tetra, Aphyocharax anisitsi

Not as common in the shops, but well worth keeping an eye out for is the Bloodfin tetra, Aphyocharax anisitsi. These are smaller, slimmer fish than Buenos Aires tetra, topping out around 5cm/2in, but share the same bold red finnage against a metallic blue body. Once again, minor aggression can be an issue, so stock them in a generous group. Don’t confuse these fish with the similar looking, but smaller, more delicate and truly tropical Glass bloodfin tetra, Prionobrama filigera. 

Scientific name: Aphyocharax anisitsi (Aff-ee-oh-char-axe an-iss-it-see).
Size: 5cm/2in.
Origin: Argentina, Brazil, Paraguay and Uruguay.
Water chemistry: pH 6 to 8. Moderately soft to hard water.
Temperature: 18–28°C/64–82°F.
Minimum tank size: 65 l/14 gal with a footprint of 75 x 30cm/30 x 12in.

Balmy barbs

The Cyprinids (carps and minnows) are the largest family of fish, so it’s not really a surprise that they include many ideal temperate subjects beyond the goldfish.

 Odessa barb,  Pethia padamya.

Odessa barb, Pethia padamya.

The stunning Odessa barb, Pethia padamya, is a fish so brightly coloured that due to the manner of its less than conventional introduction to the hobby from Myanmar via the then Soviet dominated Ukraine, it attracted claims that it was a man-made hybrid or artificially dyed. Thankfully all this was cleared up with the discovery of wild populations so we are now able to appreciate them for what they are — one of the best temperate choices of fish available.

Scientific name: Pethia padamya (Peth-ee-ah pad-am-yah).
Size: 4.5cm/1.8in.
Origin: Myanmar.
Water chemistry: pH 6.5 to 8. Moderately soft to hard water.
Temperature: 16–25°C/59–77°F.
Minimum tank size: 65 l/14 gal with a footprint of 75 x 30cm/30 x 12in.

 Black ruby barb,  Pethia nigrofasciata

Black ruby barb, Pethia nigrofasciata

When it comes to sporting tiger stripes, there are a plethora of banded beauties among the barbs. While many of these fish are either too belligerent or too tropical to be considered for temperate tanks a noteworthy exception is the handsome Black ruby barb, Pethia nigrofasciata. In the shops these often look like a washed out Tiger barb, but once settled into your tank with a good mix of sexes, males develop a deep purple-black body colour fading to ruby red around the head, speckled with metallic silver scales, like the sky at night. Females remain simply boldly striped, but their presence encourages the male’s best colour and courtship displays.

Scientific name: Pethia nigrofasciata (Peth-ee-ah nig-row-fash-ee-ah-ta).
Size: 5.5cm/2.2in.
Origin: Sri Lanka.
Water chemistry: pH 5.5 to 7.5. Soft to moderately hard water.
Temperature: 18–27°C/64–80°F.
Minimum tank size: 65 l/14 gal with a footprint of 75 x 30cm/30 x 12in.

 Rosy barb,  Pethia conchonius.

Rosy barb, Pethia conchonius.

If you’re a sucker for goldfish but don’t have a vast tank or space for a pond then the Rosy barb, Pethia conchonius is the obvious choice; all the charm and colour of the goldie but with an adult size seldom exceeding 8cm/3.2in. Selective breeding over decades means a range of colour forms are now seen, as well as a flowing finned ‘comet’ type, which is far removed from the wild fish but still very popular.

Scientific name: Pethia conchonius (Peth-ee-ah con-cone-ee-us).
Size: 6.5–9cm/2.5–3.5in. l Origin: Pakistan, India, Bangladesh and Nepal.
Water chemistry: pH 6 to 8. Slightly hard to hard water preferred.
Temperature: 16–24°C/59–75°F.
Minimum tank size: 80 l/17 gal with a footprint of 90 x 30cm/36 x 12in.

 Red-lined torpedo barb,  Sahyadria denisonii

Red-lined torpedo barb, Sahyadria denisonii

A barb that has taken the hobby by storm in the last decade has been the Red-lined torpedo barb, Sahyadria denisonii. Their striking, shark like silhouette, attractive, bold colouring
and peaceful nature has seen them rise to the heights of aquarium ubiquity alongside Neon tetras and angelfish. However, what is not so well known is the fact that these fish aren’t best served in the permanent summer of tropical tanks, where their metabolism is on fast-forward and their lifespan shortened as a result. In the temperate aquarium they will keep pace with seasonal changes and live longer, more natural lives. As with most barbs, they do best when kept in larger groups and look especially impressive holding station with just a sporadic flip of
their forked tail against the steady current of a flow pump, breaking formation occasionally to snatch a passing morsel.

Scientific name: Sahyadria denisonii (Sa-hee-ad-ree-ah den-iss-own-ee-eye).
Size: Around 10cm/4in.
Origin: Southern India.
Water chemistry: pH 6.5 to 7.5. Moderately soft to hard water.
Temperature: 15–25°C/59–77°F.
Minimum tank size: 160 l/35 gal with a footprint of 120 x 45cm/48 x 18in.

Sub-tropical substrate huggers

Once you’ve packed the upper layers of your tank with colourful barbs, danios or tetras you’ll probably want to balance things out with some bottom dwelling species. There are plenty of candidates to be plucked from the ‘tropical’ section that will appreciate cooler conditions.

 Panda  Garra, G. flavatra

Panda Garra, G. flavatra

My personal favourite is the comical Panda Garra, G. flavatra. These boldly banded beauties are great algae munchers but should never be bought for simply this purpose. They do best in groups of five or more where their hierarchical tussles make fascinating viewing.

Scientific name: Garra flavatra (Ga-raa fla-vat-raa).
Size: 8cm/3.2in.
Origin: Western Myanmar.
Water chemistry: pH 6.5 to 7.5. Soft to moderately hard water.
Temperature: 18–27°C/64–80°F.
Minimum tank size: 80 l/17 gal with a footprint of 90 x 30cm/36 x 12in.

 Yo-yo loach,  Botia almorhae

Yo-yo loach, Botia almorhae

The classy looking Yo-yo loach, Botia almorhae, is another unexpected temperate treat. These handsomely marked fish get their common name from their juvenile markings which appear on many fish as a series of black-brown y’s and o’s over a cream background. As the fish matures the patterning breaks up to a more regular reticulation, but is still lovely. Like most Botiid loaches they are social and should be kept in groups of at least five to prevent the smallest fish being picked on.

Scientific name: Botia almorhae (Bow-tee-ah al-more-ay).
Size: 14cm/5.5in.
Origin: India, Nepal and Bangladesh.
Water chemistry: pH 6 to 7.5. Soft to slightly hard water.
Temperature: 18–27°C/64–80°F.
Minimum tank size: 160 l/35 gal. with a footprint of 120 x 45cm/48 x 18in.

 Red-spotted goby,  Rhinogobius rubromaculatus

Red-spotted goby, Rhinogobius rubromaculatus

If you’re after a real character fish for your tank then look no further than the Red-spotted goby, Rhinogobius rubromaculatus. These charming little micro-predators are always on the look-out for something to eat. Males in breeding colour are gorgeous, a lovely soft powder blue covered in scarlet spots with the edges of their fins highlighted in bright white. Females are more washed out, with pale yellow fin edges but without a mix of the sexes you won’t see the fantastic head shaking, ‘gaping’ displays as males spar with each other and try to woo interested females. These gobies require good levels of dissolved oxygen and are evolved to live in areas with strong water flow.

Scientific name: Rhinogobius rubromaculatus (Rye-no-go-bee-us roo-bro-mak-you-lah-tuss).
Size: 5cm/2in.
Origin: Taiwan.
Water chemistry: Moderately soft to slightly hard water.
Temperature: 15–25°C/59–77°F.
Minimum tank size: 50 l/10 gal with a footprint of 60 x 30cm/24 x 12in.

Cool cats

Few tanks are complete in my book without a catfish or two. Many of us will know that the Peppered cory, Corydoras paleatus will get along nicely in temperate tanks.

 Three-lined cory,  Corydoras trilineatus

Three-lined cory, Corydoras trilineatus

Less well known is that the Three-lined cory, Corydoras trilineatus, (often sold as C. julii) is also well adapted to cooler water.

Scientific name: Corydoras trilineatus (Coor-ee-door-ass try-lin-ee-ah-tuss).
Size: 5.5cm/2.2in.
Origin: Amazon basin in Peru, Brazil and Colombia.
Water chemistry: pH 6 to 7.5. Soft to slightly hard water.
Temperature: 16–25°C/60–77°F.
Minimum tank size: 50 l/10 gal with a footprint of 60 x 30cm/24 x 12in.

 Bearded cory,  Scleromystax barbatus

Bearded cory, Scleromystax barbatus

Add to this their flashy big cousin the Bearded cory, Scleromystax barbatus, and you have a couple of nice alternatives to Peppered corys.

Scientific name: Scleromystax barbatus (Ss-leh-row-miss-tax bar-bay-tuss).
Size: 10cm/4in.
Origin: South Eastern Brazil.
Water chemistry: pH 5.5 to 7.5. Soft to slightly hard water.
Temperature: 16–24°C/60–75°F.
Minimum tank size: 50 l/10 gal with a footprint of 60 x 30cm/24 x 12in.

 Hoplo catfish,  Megalechis thoracata.

Hoplo catfish, Megalechis thoracata.

For larger tanks or bigger, more robust midwater fish that might intimidate corys, look instead at those seemingly indestructible, animated armoured sausages ‘Hoplos’, Megalechis thoracata, which are easily able to deal with bolshy barbs and cooler temperatures.

Scientific name: Megalechis thoracata (Mega-lek-iss thaw-a-cart-ah).
Size: 15cm/6in.
Origin: Brazil, Peru, Trinidad, Guyana, Martinique, Venezuela and Paraguay.
Water chemistry: pH 5.5 to 8. Soft to hard water.
Temperature: 17–28°C/62–82°F.
Minimum tank size: 160 l/35 gal with a footprint of 120 x 45cm/48 x 18in.

Cool — but not cold!

While all these fish can make a fantastic display at lower than tropical temperatures it is vital they don’t get too cold. Even in a modern, centrally heated house things can cool off considerably at night so adding a heater, set at the lower end of your chosen fishes’ range is a wise precaution. Similarly, just as some of these fish will suffer if kept permanently at the high end of their tolerance, they will not all appreciate being kept at the bottom end constantly — who wants to live in a permanent state of winter?

Consider creating an artificial summer or dry season period where the temperatures are elevated to the upper end of the fishes’ range — in the majority of UK houses this will happen naturally each summer even given our often less than tropical weather!