Xingu River ray Xingu River ray The Xingu River ray, white-blotched river stingray, or polka-dot stingray ("Potamotrygon leopoldi") is a species of freshwater fish in the family Potamotrygonidae. It is endemic to the Xingu River basin in Brazil and prefers rocky bottoms. It is sometimes kept in aquaria. "P. leopoldi" reaches up to in disc width, in total length and in weight. Females grow larger than males. It is closely related to the similar "P. henlei" from the Tocantins River basin and "P. albimaculata" from the Tapajós River basin. Compared to "P. henlei", "P. leopoldi" is deeper black above and its underparts are
Clearwater river (river type) Madeira (notably Guaporé, Ji-Paraná and Aripuanã) and Paraguay (although heavily influenced by its whitewater tributaries). The Tapajós and Xingu alone account for 6% and 5%, respectively, of the water in the Amazon basin. Examples of clearwater rivers originating in the Guiana Shield include the upper Orinoco (above the inflow of the blackwater Atabapo and whitewater Inírida–Guaviare), Ventuari, Nhamundá, Trombetas, Paru, Araguari and Suriname. Outside South America the classification is not commonly used, but rivers with clearwater characteristics are found elsewhere, such as the upper Zambezi River, certain upland streams in major river basins of South and Southeast Asia, and many