Ocellate River Stingray

12/04/2021 Off By Andy Ptyushkin

The Ocellate River Stingray (Potamotrygon motoro), 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.

Like other members of the genus it inhabits a variety of biotopes. These include sandbanks, the shallows of major rivers and slow-moving tributaries with substrates of mud or sand. It also moves into areas of flooded forest during the annual wet season and can later be found in terrestrial lakes and ponds formed by the receding floodwaters.

Orinoco Delta

Orinoco Delta

Potamotrygon motoro can grow up to 50 cm (1.6 ft) in disc width, 1 m (3.3 ft) in total length, and 35 kg (77 lb) in weight. Its disk is roughly circular in shape, and its eyes are raised from the dorsal surface. The dorsal colouration is typically beige or brown, with numerous yellow-orange spots with dark rings. Its exact colour and the arrangement and size of the spots can vary significantly, both from individual to individual and depending on location. Three primary types have been identified in the Amazon basin, but each of these includes a number of subtypes (two additional main types now are considered separate species, Potamotrygon marquesi). The two main Amazonian types, informally known as CD1 and CD2, are found throughout much of the Amazon (except most of the Rio Negro basin) and they often occur together. Those from the Río de la Plata Basin and Mearim River resemble CD1. Individuals from the Rio Negro and Orinoco basins (which are connected by the Casiquiare canal) are similar to each other and informally known as CD3, but differ from Potamotrygon motoro elsewhere. Some individuals of CD3 have spots near the rim of the disc that are connected, forming a chain-like pattern. However, the «marbled» type is generally only reported from the Orinoco basin, including the Ventuari River.

Rays are among the top predators in the ecosystems they populate in nature and are unsafe to keep with most other species. Conversely, they also seem to prefer a quiet life and will often fail to thrive when kept alongside very aggressive or territorial companions. The best tankmates are large enough not to be eaten, peaceful and ideally occupy the upper parts of the tank. Some cichlids, such as Heros or Geophagusspecies work well, as do many bigger characins and cyprinids. Plenty of enthusiasts keep Asian or South American arowana with their rays, and in a roomy tank, this can be a very striking combination. Other suitable options include Cichla or Datnioides spp., and in a tank with a very large footprint other bottom dwellers such as bichirs or Pimelodid catfish (Brachyplatystoma tigrinum is a popular albeit expensive choice). Obviously, all these species grow to an impressive size so tank volume should be the primary consideration before any choices are made.