River stingrays or freshwater stingrays are Neotropical freshwater fishes of the family Potamotrygonidae in the order Myliobatiformes, one of the four orders of batoids, cartilaginous fishes related to sharks. They are found in rivers in tropical and subtropical South America. A single marine genus, Styracura, of the tropical West Atlantic and East Pacific are also part of Potamotrygonidae. They are generally brownish, greyish or black, often with a mottled, speckled or spotted pattern, have disc widths ranging from 31 to 200 centimetres (1.0–6.6 ft) and venomous tail stingers. River stingrays feed on a wide range of smaller animals and the females give birth to live young. There are more than 35 species in five genera.
The roughback whipray is a rare species of freshwater stingray in the family Dasyatidae, found over sandy bottoms in the Mae Klong and Chao Phraya Rivers of Thailand. Growing no more than 29 cm (11 in) across, this small ray has an oval pectoral fin disc and a whip-like tail without fin folds. It closely resembles the white-edge freshwater whipray in appearance, but can be distinguished by its coloration: light gray to dark orange-brown above and white below with a dark band along the lateral margins. Another identifying feature is a "pearl organ" at the center of the back, found in individuals of all ages. All of the original specimens of the roughback whipray were found with extensive wounds to the fins and tail. The International Union for Conservation of Nature (IUCN) has assessed this species as Endangered, citing the extensive habitat degradation and heavy fishing pressure within its limited range.
The long-tailed river stingray or antenna ray is a species of freshwater stingray in the family Potamotrygonidae. It is found in the Amazon basin in South America, ranging from Ecuador to Belém. It lives in the main channel of the Amazon River and lower parts of its major tributaries.
Plesiotrygon, the antenna rays, is a small genus of freshwater stingrays in the family Potamotrygonidae endemic to the Amazon basin in South America. They are found in large rivers and the lower part of their tributaries. The maximum disc width is up to 58 cm (23 in), but both species are very long-tailed.
The bluespotted ribbontail ray is a species of stingray in the family Dasyatidae. Found from the intertidal zone to a depth of 30 m (100 ft), this species is common throughout the tropical Indian and western Pacific Oceans in nearshore, coral reef-associated habitats. It is a fairly small ray, not exceeding 35 cm (14 in) in width, with a mostly smooth, oval pectoral fin disc, large protruding eyes, and a relatively short and thick tail with a deep fin fold underneath. It can be easily identified by its striking color pattern of many electric blue spots on a yellowish background, with a pair of blue stripes on the tail.
The ocellate river stingray, also known as the peacock-eye stingray or black river stingray, is a species of freshwater stingray in the family Potamotrygonidae. It was the first species to be described in the family and is also the most widespread, ranging throughout much of the Río de la Plata, Amazon, Mearim and Orinoco basins in tropical and subtropical South America. It is sometimes kept in aquaria.
Potamotrygon is a genus of freshwater stingrays in the family Potamotrygonidae native to the rivers of South America, and sometimes seen in the aquarium trade.
The Mekong freshwater stingray, Hemitrygon laosensis, is a species of stingray in the family Dasyatidae, restricted to the Mekong and Chao Phraya Rivers in Laos and Thailand; the occurrence in Chao Phraya is considered an introduction. Measuring up to 62 cm (24 in) across, this ray has an oval pectoral fin disc, a tail with both upper and lower fin folds, and a midline row of spine-like dermal denticles. A characteristic feature of this species is its bright orange underside. The Mekong freshwater stingray preys on invertebrates and is aplacental viviparous. It has been assessed as Endangered by the International Union for Conservation of Nature (IUCN), as it is threatened by overfishing and habitat degradation.
The bigtooth river stingray or Tocantins River ray 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.
The Xingu River ray, white-blotched river stingray, or polka-dot stingray is a species of freshwater fish in the family Potamotrygonidae. It is endemic to the Xingu River basin in Brazil and as such prefers clear waters with rocky bottoms. It is sometimes kept in aquaria, like its more common relative the Motoro.
The raspy river stingray, mosaic stingray or arraia is a species of freshwater fish in the family Potamotrygonidae. This stingray is endemic to the Amazon basin in Brazil, where known from the Amazon–Pará River, the Madeira River basin, Uatumã River and lower Tocantins River.
The porcupine river stingray is a species of river stingray in the family Potamotrygonidae, the type of the Potamotrygon genus. It is found in the basins of the Paraná and Paraguay River basins in South America. Most chemical weathering of minerals seems to take place in the upland drainage basins rather than on the floodplains, and most major solutes display conservative mixing in the river-floodplain system. The population in the Rio Negro basin was described as a separated species, P. wallacei, in 2016.
The short-tailed river stingray is a species of river stingray native to the Río de la Plata Basin in South America. It is sometimes known as the giant freshwater stingray, but this name is typically used for the southeast Asian Urogymnus polylepis.
Heliotrygon is a genus of freshwater stingrays in the family Potamotrygonidae. The genus is endemic to the Amazon basin in South America. Despite being discovered decades earlier, the genus was only scientifically described in 2011. They mainly live in deep river channels, but approach the shore at night to feed on fish.
Heliotrygon rosai, or Rosa's round ray, is a species of freshwater fish in the family Potamotrygonidae. It is native to the Amazon basin in South America. Its maximum disc width is 80 cm (2.6 ft) and the stinger is greatly reduced, rendering it virtually harmless. It has not been evaluated by the IUCN red list.
Potamotrygon tatianae, the Tatiana's river stingray, is a species of river stingray (Potamotrygonidae) endemic to the Madre de Dios River and upper Madeira River basins in Peru.
Heliotrygon gomesi, or Gomes's round ray, is a species of freshwater stingray native to the western Amazon basin in South America, specifically Brazil. It is the type species of its genus. It spends the day in deep river channels, but moves closer to the shore at night to feed.
Paratrygon aiereba is a cartilaginous fish in the family Potamotrygonidae from the Amazon basin in South America.
Potamotrygon falkneri, the largespot river stingray or reticulated freshwater stingray, is a species of freshwater stingray in the family Potamotrygonidae from tropical and subtropical South America. It is sometimes seen in the aquarium trade, but requires a very large tank.
Potamotrygon tigrina, also known as the tiger river stingray, is a species of freshwater ray in the family Potamotrygonidae. This endangered species is endemic to black- and whitewater rivers in the upper Amazon basin in northeastern Peru. It is sometimes kept in aquariums and has been bred in captivity, but it is generally a sensitive species.
