Ancistrus is a genus of nocturnal freshwater fish in the family Loricariidae of order Siluriformes, native to freshwater habitats in South America and Panama. Fish of this genus are common in the aquarium trade where they are known as bushynose or bristlenose catfish. In the aquarium hobby they are often referred to as bushynose or bristlenose plecos instead, but this may lead to confusion as "pleco" usually is used for Hypostomus plecostomus and its allies and is often used as a catchall term for any loricariids remotely resembling that species.
Acestrorhynchus is a genus of 14 species of characiform fish found only in fresh water in South America, the sole genus in the family Acestrorhynchidae. Their greatest diversity is in the Orinoco and Amazon basins.
Hyphessobrycon is a genus of freshwater fish in the family Characidae. These species are among the fishes known as tetras. The genus is distributed in the Neotropical realm from southern Mexico to Río de la Plata in Argentina. Many of these species are native to South America; about six species are from Central America and a single species, H. compressus is from southern Mexico.
Astyanax is a genus of freshwater fish in the family Characidae of the order Characiformes. Some of these fish, like many of their relatives, are kept as aquarium pets and known collectively as tetras. With around 150 described species and new ones being described yearly, this genus is among the largest of the entire order; Hyphessobrycon also has more than 145 species and which one is larger at any one time depends on whether more species have been recently described in one or the other. The blind and colorless cave tetra of Mexico is a famous member of the genus, but its taxonomic position is disputed: Some recognize it as part of the Mexican tetra and this is supported by phylogenetic evidence, but others recognize the cave form as a separate species, A. jordani.
Serrasalmus is a genus of piranhas. They are collectively known as pirambebas; the "typical" piranhas like the piraya piranha are nowadays placed in Pygocentrus. Like all piranhas, Serrasalmus are native to South America.
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.
Copella is a genus of freshwater fish belonging to the family Lebiasinidae, native to South America, known colloquially to aquarists as splashing tetras or splash tetras, because of the unique reproductive method of the best-known representative of the genus, Copella arnoldi. They are not as closely related to the tetras proper in the Characidae as initially believed.
Spectracanthicus is a genus of suckermouth armored catfish endemic to the Tapajós, Xingu and Tocantins river basins in Brazil where often found in fast-flowing waters. The largest species in the genus reaches up to 13 cm (5.1 in) in standard length. They feed on algae and small invertebrates.
Pimelodella is a genus of three-barbeled catfishes.
Ageneiosus is a genus of driftwood catfishes found mostly in South America with one species extending into Central America.
Moenkhausia is a genus of freshwater fish in the family Characidae native to tropical and subtropical South America. These are medium-sized tetras where the largest species only reach around 12 cm (4.7 in).
Bryconamericus is a genus of characins found in Central and South America.
Hemigrammus is a genus of freshwater fish in the family Characidae native to South America and commonly seen in the aquarium trade. These are medium-small tetras where the largest species reach up to around 11 cm (4.3 in).
Knodus is a genus of characins, small freshwater fish from South America.
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.
Odontostilbe is a genus of characins from tropical Central and South America, with 17 currently recognized species:
Characidium is a genus of fish in the family Crenuchidae. They are mainly found in South America, but C. marshi is from Panama. They are small, slender fish that live on the bottom in flowing fresh waters and feed on small animals such as insects.
Hemiodus is a genus of halftooths from South America with the greatest species richness in the Amazon Basin, but also found in the Orinoco, Essequibo, Paraná–Paraguay and Parnaíba River basins. Depending on the species involved, these elongate fish reach a length of 7–30 cm (3–12 in).
Pyrrhulina is a genus of freshwater fishes found in tropical South America. Several of these species are popular aquarium fish.
Nemuroglanis is a genus of three-barbeled catfishes. With the exception of N. panamensis from Panama, they are native to tropical South America.
