Bigtooth river stingray

The bigtooth river stingray or Tocantins River ray ("Potamotrygon henlei") is a species of freshwater fish in the family Potamotrygonidae. It is endemic to the lower Tocantins basin and Araguaia basin in Brazil, and prefers muddy bottoms. It is sometimes kept in aquaria. This stingray is generally common and its population increased after the Tucuruí Dam was completed, unlike many other species in its range.
Appearance and relatives.
"P. henlei" reaches up to in disc width and in total length. It is replaced by the closely related "P. rex" in the mid and upper Tocantins basin, but that species has concentrically clustered yellow-orange spots. Two other close relatives where the spots are yellowish-white (as in "P. henlei") are found in other Brazilian rivers: "P. leopoldi" from the Xingu River basin and "P. albimaculata" from the Tapajós River basin. Compared to "P. leopoldi", "P. henlei" is duller above, appearing blackish or dark gray-brown (as opposed to deeper black in "P. leopoldi"), and its underparts have a large white center and broad brownish-dusky edges (underparts mostly brownish-dusky in "P. leopoldi"). Compared to "P. albimaculata", "P. henlei" has larger yellowish-white spots above.