Hemiancistrus medians[1] is a species of catfish in the family Loricariidae.

It is native to South America, where it occurs in the Maroni basin.

This species is usually found in rapids with a strong current and a substrate of large, shelter-providing rocks.

It is known to coexist with the species Bryconops caudomaculatus, Chasmocranus longior, Harttia surinamensis, Hypostomus gymnorhynchus, Jupiaba meunieri, Leporinus granti, and Parodon guyanensis.

This species is large for a loricariid, reaching 39 cm (15.4 inches) in total length.