Pterygoplichthys is a genus of large armored suckermouth catfish in the family Loricariidae, native to South American lowland rivers in Brazil, Peru, Bolivia, Colombia, Venezuela, Ecuador, Argentina, and Paraguay. The atlas's 15 species range from about 8 in to a substantial 27.5 in and are commonly known as sailfin plecos or sailfin catfish, for the tall, many-rayed dorsal fin that sets the genus apart from most other plecos at a glance. Like other loricariids they carry a bony-plated body and a ventral suckermouth for grazing algae and biofilm, but their large adult size and tolerance of a wide range of water conditions have made several species unusually successful outside their native range as well as inside it.
This is one of the aquarium hobby's most familiar pleco genera: the sailfin pleco (Pterygoplichthys gibbiceps), Amazon sailfin catfish (P. pardalis), vermiculated sailfin catfish (P. disjunctivus), and Orinoco sailfin catfish (P. multiradiatus) are all widely sold, usually bought small and undersized for the tank they end up needing once they grow. That same hardiness and appetite has made Pterygoplichthys one of freshwater fishkeeping's best-documented invasive genera, with released or escaped fish established in Florida, parts of Asia, and elsewhere well outside South America. In its native range, the picture is reassuring for a widely traded genus, with fourteen of the fifteen species assessed as Least Concern and just one carrying a Vulnerable rating.