Pareiorhaphis is a genus of small armored catfish in the family Loricariidae, subfamily Neoplecostominae, the same lineage as Neoplecostomus and Isbrueckerichthys, and like its relatives it is endemic to Brazil, found only in the fast, rocky headwater streams of the country's southeastern highlands. Species are small to modest in size, from about 1–6.5 in in the atlas's range, with a flattened body and enlarged, often bristled cheek plates used in male-to-male sparring, an unusually visible display for a suckermouth catfish. The atlas covers 25 species.
In the aquarium world Pareiorhaphis is a specialist's fish rather than a shop staple, appealing to keepers of cool-water, high-flow biotope tanks who want an alternative to the more familiar Otocinclus and Ancistrus, grazing algae and biofilm off rock in strongly oxygenated water. Species such as the splendid needle-jaw pleco (P. splendens) and Regan's bristlemouth pleco (P. regani) show the genus's typical bristled, needle-toothed mouth. Most assessed species are least concern, but a handful are ranked near threatened or endangered, a reminder that a Brazil-only genus built from narrow highland stream ranges is exposed to any single watershed's degradation.