Wikipedia
Potamotrygon is a genus of freshwater stingrays in the family Potamotrygonidae native to the rivers of South America. Freshwater stingrays of this genus are sometimes kept as exotic aquarium fish; though freshwater stingray of other genera do appear in the trade, most are from this genus. They are best kept with a deep, sandy substrate, in which they bury themselves, often with only the eyes visible. They are not territorial with other animals and can be kept in groups, provided a large enough aquarium is provided. They are carnivorous bottom feeders and require strong filtration as they are rather sensitive to water conditions. Many species of stingray have been bred in captivity and males can be determined by the presence of claspers as in other Chondrichthyans.
Like other stingrays, the fishes of this genus have venomous barbs at the base of their tails, and are dangerous species to humans. It is said that the natives of South America fear the stingray more than they do the piranha. An undescribed type is referred to as the Itaituba river stingray or P14 (a P-number system is sometimes used by aquarists, similar to the L-number system). This fish is superficially similar to P. henlei and P. leopoldi except for smaller spots and in larger number.