Slender Hemiodus

About

The slender hemiodus (Hemiodus gracilis) is a sleek, torpedo-shaped characin from the major river systems of South America, including the Amazon, Orinoco, Negro, Madeira, Tapajós, and Solimões basins. It belongs to a group of similar-looking species that can be tricky to tell apart without a close look at body patterning. H. gracilis is probably the one you're most likely to encounter at a fish store, where it occasionally turns up under the name red hemiodus or red-tailed hemiodus. In the aquarium it's a genuinely peaceful fish, but its size and restless, fast-moving nature can stress smaller or more timid tankmates, so choose companions wisely. It works best alongside other mid-to-large characins, eartheater cichlids like Geophagus or Satanoperca, and robust catfish or loricariids. Exactly the kind of community you'd build around a large Amazon biotope. This is a true shoaling species, and keeping fewer than ten together tends to result in skittish, unsettled fish. Given plenty of space and a proper group, they usually calm down after an initial adjustment period. Breeding in captivity hasn't really been documented, and this species remains uncommon enough in the hobby that intermediate experience with larger South American fish is a reasonable baseline before taking them on.