Freshwater stingrays are a fish family related to marine stingrays and sharks. The tectonic movements that led to the drift of the South American continent, at different times in its geological history, and the rise of the Andes, probably favored the penetration of some marine species, as is the case of the Potamotrygonidae family. The species of this family are widely distributed in the lowland rivers of the continent. The highest richness is found in the Amazon basin, with 22 out of 31 known species.
These animals are surprisingly beautiful due to their almost circular body shape, which ends in a tail with a sting on the tip, and by the different patterns they exhibit. The skin of most species has gray, and light and dark brown tones. They present designs in the form of spots, rings, speckles, rounded or hexagonal rosettes and dots, of white, blue, violet, orange or light brown colors, which give them uniqueness.
Stingrays studies in Bolivia are still scarce. It is one of the least known fish groups, considering the 900 species of registered fish species. Ichthyologists from the National Museum of Natural History and the Wildlife Conservation Society carried out a first analysis of the existing knowledge in Bolivia about freshwater stingray diversity, richness and ecology, published in the book 'Freshwater Stingrays (Potamotrygonidae) of South America', led by the Alexander von Humboldt Institute. So far, five species of the Amazon and Paraguay-Paraná basin rivers have been described: Paratrygon aiereba, Potamotrygon falkneri, Potamotrygon motoro, Potamotrygon orbignyi and Potamotrygon tatianae. Four of these species have been identified within Madidi National Park.
The adult freshwater stingray size varies between 26 and 83 cm disc width, and 25 and 92 cm disc length; however, some species, such as P. motoro, may have a larger size. They are viviparous animals, with low fecundity rate, so they can be susceptible to environmental impacts. Although they have not been included in the list of threatened species in Bolivia, due to lack of information, it is known that in recent years their commercial use by aquariums has increased, as in other countries of the continent.