Paratrygon is a genus of South American freshwater stingrays in the family Potamotrygonidae, found in Amazon and Orinoco river systems across Brazil, Colombia, Venezuela, Bolivia, Ecuador, and Peru. The atlas covers 7 species ranging from about 12 in up to a metre across, and the genus is best known by its common name, discus ray, for a disc that is unusually round and smooth-edged compared with the more angular outlines of many other river stingrays. Like other potamotrygonids they are bottom-dwellers, resting half-buried in sand or mud by day and carrying a venomous barbed tail spine for defense, and they are ovoviviparous, bearing a small number of well-developed live young rather than laying eggs.
The genus is a long-standing name in the freshwater stingray trade, where the discus-shaped body and often striking dorsal patterning make species such as Paratrygon aiereba, the ceja, popular with specialist ray keepers willing to provide the large, soft-substrate tanks and careful handling the venomous spine demands. Several of the species now recognized, including P. araguaia, P. munduruku, P. lucindai, and P. orinocensis (Orinoco discus ray), reflect fairly recent taxonomic splitting of what was once treated as a single wide-ranging species into a set of more narrowly distributed forms. The IUCN picture is mixed and includes one Critically Endangered and two Vulnerable species, consistent with the slow reproduction, restricted ranges, and ongoing pressure from collection and river habitat change that affect freshwater stingrays generally.