Pseudogastromyzon is a genus of hillstream loaches native to fast-flowing streams in China and Malaysia. The atlas covers 7 species ranging from about 1.5 in up to 3 in, and like other hillstream loaches they carry a flattened, ventrally depressed body and enlarged paired fins that fan out into a suction-like disc, letting them cling to smooth rock in strong current rather than being swept downstream. That same body plan puts a limit on how big and heavy-bodied these fish can get, which is why the whole genus stays small. They are algae grazers, using a sucker-like mouth to rasp biofilm and algae off stone surfaces in cool, highly oxygenated water.
Several species are genuine hobby staples for the specialist high-flow, "river tank" style of aquarium, most notably Pseudogastromyzon fasciatus, the banded hillstream loach, which is widely kept as an algae-eating companion for fast-current setups and needs strong water movement and well-oxygenated conditions to thrive rather than the still water many community tanks provide. Others, such as the striking Pseudogastromyzon meihuashanensis (red panda loach), are prized by collectors for colour and pattern but remain more of a niche interest. Conservation status is mixed, with most species Least Concern or Not Evaluated and one listed as Near Threatened, suggesting some populations face localized pressure even as the genus as a whole is not considered broadly at risk.