Chinese Algae-eater Gyrinocheilus aymonieri

The Chinese Algae-eater, also called Sucking Loach and, wrongly, Siamese Algae-eater (a separate species and genus) is native to rivers, streams, and flooded forests of Indochina. It can grow to 28cm long and has a low, sucking mouth like a loach. It is an olive brown or grey colour with dark lateral blotches, a faded line or even a solid dark lateral line. It has small "ears" on the top of its head. These are extra gill outlets; unusually it takes water in through one set of gills and out through the other so that it can continue to use its suckerlike mouth to hold on to surfaces in fast-flowing water. Its relative, the Spotted Algae-eater, Gyrinocheilus pennocki can look similar, as can even Eurasia's unrelated Common Gudgeon.

A wholly golden variant has been bred in aquaculture, where they are valued for eating tank algae, in addition to a variant with a gold (or yellow or orange) head.