Homalopterula is a genus of small hillstream loaches found in Southeast Asia, with atlas records from Indonesia, Myanmar, and Thailand. Like other hillstream loaches, its body is flattened and elongated, an adaptation for clinging to rock and gravel in fast, well-oxygenated current rather than swimming freely in open water; the six atlas species are small, running 2–3 in as adults. Data on this genus is thin - two of six species are Data Deficient and two more are Not Evaluated, leaving only one Least Concern and one Near Threatened assessment, a sign of how little formal survey work has reached this group of fast-water Southeast Asian streams.
This is a genus of specialist and scientific interest rather than mainstream aquarium trade; H. ripleyi, the Ripley's hillstream loach, carries the only common name among the six species the atlas lists, while the rest - H. amphisquamata, H. gymnogaster, H. heterolepis, H. modiglianii, and H. vanderbilti - are essentially unknown outside ichthyological literature. Where hillstream loaches of this general body plan do appear in the trade, hobbyists keep them in high-flow, well-oxygenated tanks with algae growth for grazing, mimicking the fast rocky streams the genus is adapted to.