Gymnotus is a genus of Neotropical freshwater fish in the family Gymnotidae found widely in South America, Central America and southern Mexico. The greatest species richness is found in the Amazon basin. They are sometimes referred to by the English name banded knifefish, although this typically is reserved for the most widespread species, G. carapo. Overall Gymnotus is the most widespread genus in the order Gymnotiformes.
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.
The firewood catfish a species of South American pimelodid catfish, is the sole member of the genus Sorubimichthys. Known by locals along the Amazon Basin as peixe-lenha, the firewood catfish is so called because it is of little eating value and is often dried and used for firewood.
Exallodontus aguanai is a catfish species of the monotypic genus Exallodontus of the family Pimelodidae. This genus and species was described in 1991. This species reaches 20 centimetres (7.9 in) SL. This species is native to the Amazon and Orinoco River basins of Brazil, Colombia, Peru and Venezuela. Exallodontus is classified under the "Calophysus-Pimelodus clade". Within this clade, it is considered a part of the "Pimelodus-group" of Pimelodids, which also includes Pimelodus, Duopalatinus, Cheirocerus, Iheringichthys, Bergiaria, BagropsisParapimelodus, Platysilurus, Platystomatichthys, and Propimelodus.
Cetopsis is a genus of catfishes of the family Cetopsidae.
Micromyzon is a genus of tiny catfish in the family Aspredinidae native to relatively deep parts of the Amazon and Orinoco basins in South America.
Francisco Mago Leccia (“Mago”) was born in Tumeremo, Bolívar State, Venezuela on May 21, 1931 and died in Puerto La Cruz, Anzoátegui State, Venezuela on February 27, 2004. Mago was a distinguished Venezuelan ichthyologist who specialized in electric fish of the rivers and lagoons of South America, particularly of Venezuela. His education was Docent in Biology and Chemistry graduate from the “Instituto Pedagógico de Caracas”,, Master of Sciences from the University of Miami, Florida, U.S.A., Doctor in Sciences from Universidad Central de Venezuela. His Doctoral Thesis was entitled: “Los peces Gymnotiformes de Venezuela: un estudio preliminar para la revisión del grupo en la América del Sur”.
Magosternarchus is a genus of weakly electric knifefish in the family Apteronotidae, containing two species. They are endemic to Brazil, occurring in large river channels in the Amazon River basin. Both species are unusual benthic predators that specialize in biting off the tails of other knifefishes, and are characterized by their greatly enlarged jaws and teeth. Recent systematic studies indicate that both species should be included in Sternarchella instead of being placed in their own genus.
Sternarchogiton is a genus of weakly electric knifefish in the family Apteronotidae, with four known species, all living in the main channel of large rivers in the Amazon and Orinoco basins in South America.
Apteronotus is a genus of weakly electric knifefish in the family Apteronotidae, distinguished by the presence of a tiny tail fin. This genus is restricted to tropical and subtropical South America and Panama where found in a wide range of freshwater habitats. They feed on small animals.
Compsaraia is a genus of ghost knifefishes found in tropical South America. There are currently three described species in this genus. They are found deep in large rivers in the Amazon and Orinoco basins, and have small eyes and little pigment.
Megadontognathus is a genus of ghost knifefishes found in river rapids in tropical South America. They are brown with a stubby snout and reach about 20–25 cm (8–10 in) in total length.
Platyurosternarchus is a genus of ghost knifefishes found in the Amazon, Orinoco and Essequibo river basins in tropical South America. They are medium-sized knifefish that reach up to 41.5 cm (16.3 in) in total length and have a relatively long, downwards-pointed tubular snout. They are typically found in streams or near the shore of rivers, often among submerged tree trunks and branches over a leaf-covered bottom where they find their invertebrate prey.
Sternarchella, the bulldog knifefish, is a genus of ghost knifefishes found at depths of 2–50 m (7–164 ft) in the main channel of large rivers in South America. Most are from the Amazon basin, but S. orthos is found both in the Amazon and Orinoco, S. orinoco is restricted to the Orinoco and S. curvioperculata restricted to the upper Paraná basin. They are often common in their habitat.
Sternarchorhynchus is a genus of ghost knifefishes with a long, decurved snout that are found in river basins in tropical South America.
Hypopygus is a genus of South American gymnotiform knifefishes native to the Amazon, Orinoco and upper Paraguay basins, as well as rivers in the Guianas. They are often common, and found near submerged roots, aquatic vegetation and leaf-litter in streams, edges of rivers and floodplains. They are regularly found among vegetation in floating meadows, a habitat that often contains little oxygen, but they are well-adapted to this.
Archolaemus is a genus of South American glass knifefishes. They occur in fast-flowing sections of rivers, including rapids, in the Amazon, Tocantins, São Francisco and Araguari basins. Depending on the exact species, they reach up to about 20–50 cm (8–20 in) in total length. During the day they hide in rocky crevices, but during the night they are active and feed on small invertebrates such as aquatic insect larvae.
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.
Rhabdolichops is a genus of glass knifefishes found in Amazon, Orinoco and Maroni basins in tropical South America. They live near the bottom in main river channels, floodplains and lagoons, and are typically found in relatively deep waters.
Sternopygus is a genus of glass knifefishes found in tropical and subtropical South America, and Panama. They inhabit a wide range of freshwater habitats, from fast-flowing rivers to essentially static waters in floodplains, and shallow habitats to the bottom of deep rivers. S. macrurus will even visit brackish mangrove to feed.
