E. sinensis was initially included in the genus Protomyzon where it remained until 2004 when Kottelat found sufficient geographical and morphological differences between members of the group inhabiting the island of Borneo and those from mainland East/South East Asia to warrant their separation.

The genus Erromyzon was erected to accommodate the mainland fishes and there are currently three…

This species is one of several traded variously as 'butterfly loach', 'butterfly plec', 'Hong Kong plec(o)', 'Chinese hillstream loach' or simply 'hill stream loach'. In many countries it's the most common balitorid in the shops but is also often found in mixed shipments containing members of other genera.

Like all balitorids it's an obligate bottom-dweller with specialised morphology adapted to life in fast-flowing water. The paire…

This species is also sold under the vernacular names 'golden Chinese loach' and '12-banded Chinese loach'. Along with S. robusta it's the most commonly-traded member of the genus, and the two are often imported in mixed batches, presumably because they occur and are thus collected together in nature. Like most congeners it has a highly flexible, sinuous body which makes it very interesting to observe.

S. pulchra can be differentiated from…

This species is also sold under the vernacular names 'golden Chinese loach' and '12-banded Chinese loach'. Along with S. pulchra it's the most commonly-traded member of the genus, and the two are often imported in mixed batches, presumably because they occur and are thus collected together in nature.

One of the most ubiquitous species in the hobby and several ornamental strains are available including ‘long-finned’, ‘golden’, ‘albino’, and ‘super red’, for which care is identical to that of the ‘standard’ fish.

Unfortunately the degree of inbreeding amongst farm-bred stock has resulted in a situation whereby many of the fish available today are genetically weak and prone to disease or develop physical deformities.

M. ocellatus can be distinguished from congeners by the following combination of characters: caudal-fin rounded; eye stripe not connecting spot on posterior projection of opercle with eye; dorsal-fin rays filamentous posterior to a vertical through the posterior anal-fin rays in adults; 16-19 spinous dorsal-fin rays; 6-13 rakers on ceratobranchial of first gill arch; posterior tip or margin of body scales not darker than scales.