Classic Car Intelligence
  • Species: Gambusia holbrooki

  • Species: White Cloud Mountain Minnow

  • Species: Rhinogobius wui

Some Like It Cool

When considering a fish tank, often the choice appears to be between a tropical tank and goldfish. A large number of species fall into a category between these two, as fish that will thrive well in an indoor tank without heating. This makes them especially suitable for situations where you don’t want to mix water and electricity, for example in a child’s tank, or just as something different. A temperate tank doesn’t mean any compromise on beauty or interest, and some of the fish suitable for such a tank deserve a lot more popularity than they currently enjoy.

Plants suitable for a temperate tank include elodea and java fern, both tough and hardy as well as attractive. Most pond oxygenators will settle for a life indoors – these are the plants that spend their lives totally immersed, as opposed to the marginals which only have their ‘feet’ in the water and are impractical for an indoor aquarium. Hornwort is an attractive species which can be rooted or kept floating, as is parrot’s feather, although this latter will require trimming to stop it growing out of the water.

One of my favourite fishes is the bitterling. The European bitterling, Rhodeus sericeus, is a beautiful enough fish, but some of its cousins from China are larger and even more spectacular. A bitterling in breeding colouration is a match for any tropical fish, and fortunately with a little encouragement this is nearly all the time. The encouragement required is the presence of a large swan mussel, which in its turn requires very clean, oxygenated water. Look after your mussel and the mussel will look after the bitterlings. The fish will nudge at the mussel repeatedly until it becomes inured to their attentions and doesn’t bother to close up when they are around. At this point the female bitterling will extrude a long ovipositor, which she inserts into the mussel and lays her eggs inside. The male expels his milt into the water, from where it is drawn into the mussel by its breathing action and fertilises the eggs. The little bitterlings grow inside the mussel without harming it, but where they are safe behind solid walls and with a constant supply of food drawn in for them by the mussel’s own feeding activities. To ensure they get enough you can squirt fry food around the mussel with a turkey baster a couple of times a day. Once the fry have grown enough to be able to look after themselves, they emerge from the mussel and swim off into the tank. All the time this is going on, the male bitterling is liveried in brilliant reds and metallic blues, and will be a conversation piece to everyone who sees him.

Many of the gobies sold as tropical fish are really temperate ones, and will be perfectly happy in an unheated tank. Rhinogobius duospilus, the dragon goby (not to be confused with the other dragon goby, Gobioides broussonnetii , which is about a foot long, tropical and bright purple) is a cute little fish that grows to just over an inch long. The females are speckled brown in colour, as is the male except when he is thinking about spawning (which is most of the time). Then he turns a deep chocolate brown, with white head markings and a brilliant red throat which he shows off at every opportunity by throwing his head back and flaring his gills. These are bottom dwelling fish that don’t really swim – rather they bounce and dart over the substrate, as well as perching on rocks and in plants playing ‘king of the castle’. Provided with a little sinking live (or frozen) food, a few plants and some flat stones, a male and a few females will live happily together. Eventually the day will come when the male appears to have vanished completely. However, don’t write him off – he will be curled up under a flat stone, having carefully spat gravel around to block up his entrance, with eggs from one or more of his wives, and will emerge ready for action again once the fry have hatched. The little fish are easy to rear if you extract them from the main tank once they have hatched – baby brine shrimp are an ideal first food and they grow to daphnia and bloodworm eating size rapidly. Taking the eggs out too early is a bad plan, as they usually fungus – the painstaking care of their father is hard to duplicate. The eggs are unusual in that each is attached to a fine stalk, which is used to fasten the eggs to the stone that the male has chosen.

White Cloud Mountain Minnows, Tanichthys albonubes, are sometimes called the poor man’s neon, which doesn’t really do them justice. They are pretty, active little fish in their own right, which are easy to keep and would much prefer an unheated tank than a tropical one. Growing to just under two inches, they are best kept in a small shoal. They are a greenish brown, with a gold and black stripe along the flank. These little fish come from mountain streams in China, and like plenty of water movement and plants to dart among. They are egg scatterers, but will normally go round and eat them afterwards. Provision of some bushy plant at the bottom, such as moss, will allow some of the eggs to go undetected. The is a variant of the White Cloud sold as the Meteor Minnow or Red Rocket Minnow, which is a long finned variety of the fish. These are hard to find in shops, but very attractive, and just as hardy and active as their shorter finned cousins.

Another Chinese fish that is happier in temperate waters, especially with good water movement, is the Chinese Hillstream Loach, Pseudogastromyzon myersi. These curious fish are flattened , with the pectoral fins extended to form a ruffle around the body. They spend their time attached to rocks, or in the aquarium the glass, cleaning off detritus and algae. These are attractively patterned in shades of brown, and grow to about 3 inches long. It is best to keep a few, and give them some nooks and crannies in which to hide. Although they do eat algae, it is best to give them some vegetable food as well to keep them in good condition. They are sometimes sold as the ‘coldwater plec’, although these are loaches, and no real relation to the catfish pleco.

For those who would like to try a livebearer, there is Gambusia affinis, the Western mosquitofish, and the more attractive Gambusia holbrooki, the Eastern mosquitofish. For a long time these were thought to be variants of the same species, but recent research has elevated holbrooki to a species status of its own. Both of these are small (one and a half inches for the males, up to three inches for the females) and easy to keep fish, that will breed with verve and enthusiasm. The Western fish is mostly grey, fading to white on the belly, but the Eastern mosquitofish male is attractively patterned with black patches, sometimes to such an extent the fish is completely black. The females are generally the same grey colour as the Eastern mosquitofish females, but some do show some of the piebald markings of the males. Each pregnancy lasts between twenty-five and thirty days, after which between ten and a hundred fry are born. Brood sizes tend to increase as the females mature. These fish will actively hunt down and eat the fry, but after a few broods of a hundred fry each you will come to see this as a blessing rather than a curse. For a temperate tank, or anyone who would like to try a ‘wild’ livebearer, the mosquitofishes are amenable and hardy little fish that can be safely kept with any tank mates not big enough to eat them.
This is just a small sampling of some of the fascinating fish that can live and thrive in an unheated tank. Although many of them are sold in the tropical sections of shops, keeping them in tropical waters will speed up and artificially shorten their lives. Most of these fish are only small, so for only a small allotment of space you can try a new project and a new range of fascinating fishes.


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