You could be forgiven for thinking that these fishes are surface dwellers, because they have long, streamlined bodies and small upturned mouths. But nothing could be further from the truth. The anostomids, sometimes referred to as “headstanders”, inhabit very fast-flowing waters in rocky stretches of rivers. They are found, head down, in narrow, vertical, rocky fissures. In the aquarium provide vertical crevices, which can be constructed from either actual rocks or plastic substitutes to lessen the weight.
Keep anostomids either as a single individual in the community aquarium, or in a group of seven or more. For reasons best known to themselves, they become very aggressive if kept in small groups – a similar situation to that encountered with Barbus tetrazona (Tiger barbs) (see Cypriniformes chapter). They are predominantly herbivores and will graze on algae and plants. In the furnished aquarium offer lettuce leaves “planted” in the substrate and the fishes will take these in preference to the aquarium plants. Peas are another suitable substitute food. Small aquatic invertebrates such as mosquito larvae and bloodworms are also relished, and young fishes will take flake foods, especially vegetable flake.
Anostomus anostomus (Striped headstander) is the species most often offered for sale. They are stunningly coloured, with dark gold and black stripes running the length of the body and bright scarlet patches at the base of the caudal fin. They adapt readily to aquarium life and will mark out territories in the tank. Provide them with strong filtration – ideally the water should be turned over twice an hour. They are reported to have been bred, but no details are as yet available.
Two other species are occasionally obtainable. Anostomus ternetzi is similarly coloured to A. anostomus, but is slightly smaller and lacks the red coloration in the caudal fin. It is a more peaceable species than A. anostomus and can be kept under similar conditions. Anostomus taeniatus also appears now and again, and is likewise a peaceful shoaling fish requiring the same aquarium conditions. It has a single black stripe along the body, with gold above and cream below. At night it changes its colouring to brown with faint cream markings.