Apareiodon is a genus of small, elongate characins in family Parodontidae, native to fast-flowing rivers and streams across South America, with atlas records from Brazil, Argentina, Guyana, Venezuela, French Guiana, Paraguay, and Suriname. Atlas species range 2–7 in, torpedo-shaped, bottom-oriented fish with a small, downturned, scraper-like mouth built for rasping algae and biofilm off rocks and submerged wood in current - the sort of stream-bed lifestyle behind common names like 'darter characin' and 'algae eater.'
Largely a genus of scientific interest rather than an aquarium staple; the Brazilian algae eater (A. machrisi) is the species most likely to appear as an occasional import for algae-conscious keepers, but the genus as a whole is little kept in the hobby. Conservation data are sparse across the group - 11 of the 15 atlas species are Not Evaluated, with just a single Near Threatened and a single Vulnerable listing among the rest, underlining how much remains unknown about status across this widely scattered, current-loving genus.