The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about 6,300,000 km2 (2,400,000 sq mi), or about 35.5 percent of the South American continent. It is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname, and Venezuela, as well as the territory of French Guiana.
The arapaima, pirarucu, or paiche is any large species of bonytongue in the genus Arapaima native to the Amazon and Essequibo basins of South America. Arapaima is the type genus of the subfamily Arapaiminae within the family Osteoglossidae. They are among the world's largest freshwater fish, reaching as much as 3 m (9.8 ft) in length. They are an important food fish. They have declined in the native range due to overfishing and habitat loss. In contrast, arapaima have been introduced to several tropical regions outside the native range, where they are sometimes considered invasive species. In Kerala, India, arapaima escaped from aquaculture ponds after floods in 2018. Its Portuguese name, pirarucu, derives from the Tupi language words pira and urucum, meaning "red fish".
Pygocentrus is a genus of the piranha family Serrasalmidae. All species are native to tropical and subtropical South America. All the species are predatory, scavengers and may form large schools. The famous red-bellied piranha, Pygocentrus nattereri, is one of four species in the genus.
Leporinus is a genus of fish in the family Anostomidae native to South America. The fossil species Leporinus scalabrinii, known from the late Miocene of Entre Ríos in Argentina, has only recently been added to this genus after being misidentified as a species of primate under the name Arrhinolemur scalabrinii for over 100 years.
Aphanotorulus is a genus of armored catfishes native to the Amazon, Orinoco, Essequibo and Jaguaribe basins in South America. They typically occur on a sand or gravel bottom in slow to moderately flowing rivers and streams, but some species occur in areas with fast current. The largest species in the genus reaches up to 51 cm (20 in) in standard length.
Trichomycterus is a genus of fish in the family Trichomycteridae, the largest genus of its family with over 170 species currently described. This genus is native to freshwater habitats in Central and South America. These fish are generally small, usually about 5 to 15 cm (2–6 in) in standard length, although the largest, T. rivulatus, can reach more than twice this size. Species differ from one another primarily in body proportions, fin ray counts and colouration. Despite their relatively small size, some, such as T. punctulatus, support fisheries and are important in the local cuisine.
Salminus brasiliensis is a large, predatory characiform freshwater fish found in central and east-central South America. Despite having Salminus in its name, the dorado is not related to any species of salmon, nor to the saltwater fish also called dorado. It is very popular among recreational anglers and supports large commercial fisheries.
Brachyplatystoma is a genus of catfish from the family Pimelodidae. As the occasionally used common name goliath catfishes indicates, this genus includes some of the largest species of catfish, including the piraíba, B. filamentosum, which reaches up to the region of 3.6 metres (12 ft) in length. Brachyplatystoma are found in the Amazon and Orinoco basins, and other tropical freshwater and brackish habitats in South America. Some species are migratory. These fish are important as food fish and, to some extent, aquarium fish.
Hypophthalmus is a genus of long-whiskered catfishes native to freshwater in tropical and subtropical South America.
Pseudacanthicus is a genus of medium to large-sized suckermouth armored catfishes native to South America, where found in the Amazon and Orinoco basins, as well as rivers of the Guianas. They are primarily found in fast-flowing waters, sometimes relatively deep. They are sometimes kept in aquariums.
Brycon is a genus of fish in the family Characidae found in freshwater habitats in Central and South America, ranging from southern Mexico to northern Argentina. Despite not being closely related to true trout, they are sometimes called South American trout. Members of the genus may be referred to by a number of other different common names in various languages. They reach a maximum length of 11.9–79.5 cm (4.7–31.3 in) depending on the species involved. Some species perform seasonal breeding migrations.
Prochilodus nigricans, or black prochilodus, is a species of prochilodontid fish from the Amazon Basin in South America. It supports major fisheries; according to IBAMA, it is the third most caught taxon in the Brazilian Amazon by weight, after Brachyplatystoma vaillantii and Semaprochilodus spp. The black prochilodus is migratory, moving between different parts of the Amazon. The black prochilodus reaches up to 45 cm (18 in) in total length and 1.2 kg (2.6 lb) in weight.
Piaractus brachypomus, the pirapitinga, is a large species of pacu, a close relative of piranhas and silver dollars, in the serrasalmid family. It is native to the Amazon basin in tropical South America, but it formerly included populations in the Orinoco, which was described in 2019 as a separate species, P. orinoquensis. Additionally, P. brachypomus is widely farmed and has been introduced to other regions. In South Florida they are invasive in rivers, canals or lakes.
Salminus, popularly known as dorado or dourado, is a genus of relatively large, predatory freshwater fish from the family Characidae. They are native to large tropical and subtropical rivers in South America, and undertake migrations during the rainy season to spawn. They are very popular among recreational anglers and also support important commercial fisheries.
Prochilodus is a genus of freshwater fish from the family Prochilodontidae. This family include two other genera, Ichthyoelephas and Semaprochilodus, which have been included in Prochilodus instead. The greatest species richness of Prochilodus is in river basins in eastern, southeastern and southern Brazil, but there are also species in the river basins of the Amazon, Guianas, Colombia, Venezuela, Paraguay and northeastern Argentina. The largest species in the genus reach about 80 centimetres (2.6 ft) in length, but most species barely reach half that size.
Myloplus is a genus of freshwater fish in the family Serrasalmidae found in tropical and subtropical South America, where they inhabit rivers and streams. They are primarily herbivores, but also take some animal matter. Depending on the exact species, they reach up to 16–56 cm (0.5–1.8 ft) in standard length. Adult males have a double-lobed anal fin and filamentous extensions on the dorsal fin, and both sexes can be brightly colored when breeding.
Mylossoma is a genus of serrasalmids from tropical and subtropical South America, including the basins of the Amazon, Orinoco, Lake Maracaibo and Paraguay-Paraná. These common fish are found both in main river sections and floodplains. They support important fisheries and based on a review by IBAMA, they are the seventh most caught fish by weight in the Brazilian Amazon. They primarily feed on plant material such as seeds and fruits, and in their ecology they generally resemble the larger tambaqui. Mylossoma reach up to 28.5 cm (11.2 in) in length and 1 kg (2.2 lb) in weight.
Eigenmannia is a genus of fish in the family Sternopygidae native to tropical and subtropical South America, and Panama. They are typically found in slow-flowing streams, along the edge of large rivers, in deep river channels and in floodplains, and the genus also includes E. vicentespelaea, the only cave-adapted knifefish. Eigenmannia are often found near submerged roots, aquatic plants and floating meadows.
The kissing prochilodus or flag-tailed prochilodus is a species of South American freshwater fish in the family Prochilodontidae. It is native to central and western parts of the Amazon basin. It is migratory, moving in large groups into whitewater rivers to spawn, afterwards returning to blackwater and clearwater rivers, as well as flooded forests. It is important in fisheries and sometimes seen in the aquarium trade, but require a relatively large tank. It can reach a maximum standard length of 27.5 cm (10.8 in) and weight of 560 g (1.23 lb). It resembles the other members of the genus Semaprochilodus, where most species are silvery with orange-red fins and a striped tail. Adult S. insignis lack the dark flank spots that can be seen in adult S. taeniurus, but both species have these spots as juveniles.
A whitewater river is classified based on its chemistry, sediments and water colour. Whitewater rivers have high levels of suspended sediments, giving the water a pH that is near-neutral, a high electric conductivity and a pale muddy, coffee and cream-like colour. Whitewater rivers are of great ecological importance and are important to local fisheries. The major seasonal Amazonian floodplains known as várzea receive their water from them.
