The polka-dotted stingray Potamotrygon leopoldi, also called Leopold's stingray, is one of several species of freshwater stingray that inhabits the rivers and streams of tropical South America. The indigenous peoples of this region fear the ray more than the infamous piranha. Closely related to their marine relatives, these fishes have a barbed tail capable of delivering a venomous sting. Leopold's stingray is considered rare but not endangered.