What are Scleromystax and where do they come from?

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I've seen some catfishes on sale as Scleromystax, but they look like Corydoras to me. What are Scleromystax and where do they come from? Matt Clarke has the answer.

Scleromystax is a small group of catfishes that were once members of the genus Corydoras. They’re now considered to be members of their own genus and thought to be more closely related to Aspidoras than to Corydoras.

There are currently four species described: S. barbatus, S. macropterus, S. prionotus and S. salmacis. They all differ markedly in appearance between the sexes (apart from S. salmacis) and are found in small tributaries and coastal river basins in southern and south-eastern Brazil, rather than in the Amazon basin where most Corydoras are found.

Scleromystax tend to prefer cooler water than Corydoras, so they don’t always do well when added to tropical tanks and really need to be kept in lower 20s°C/71-75°F temperatures.

This item was first published in the November 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.