Polyipnus is a genus of oceanic ray-finned fish in the family Sternoptychidae. This is the largest genus of the marine hatchetfishes subfamily Sternoptychinae and indeed of the entire Sternoptychidae. It is not quite as apomorphic as their relatives; it may be that the genus is actually a paraphyletic assemblage of less advanced Sternoptychinae and would need to be split.
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.
Crenicichla is a genus of cichlids native to South America commonly known as the pike cichlids. They are found in most tropical and subtropical freshwater habitats between the Andes and the Atlantic.
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.
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.
Fundulus is a genus of ray-finned fishes in the superfamily Funduloidea, family Fundulidae. It belongs to the order of toothcarps (Cyprinodontiformes), and therein the large suborder Cyprinodontoidei. Most of its closest living relatives are egg-laying, with the notable exception of the splitfin livebearers (Goodeidae).
Gila is a genus of fish belonging to the family Cyprinidae, native to the United States and Mexico. Species of Gila are collectively referred to as western chubs. The chiselmouth is a close relative, as are members of the genus Siphateles. Several members of the genus are endangered or extinct due to loss of habitat causing by diversion or overuse of water resources, particularly in the western United States.
Coryphaenoides is a genus of rattails which is found in all oceans of the world. They are found in deep waters and C. yaquinae, recorded to 7,012 m (23,005 ft), is the only member in the family known from the hadal zone.
Orestias is a genus of pupfish. Older systematics classified them into the own family Orestiidae. They are found in lakes, rivers and springs in the Andean highlands of South America, and several species are considered threatened. They are egg-laying fish that feed on small animals and plant matter. The largest species can reach a total length of 27 cm (10.6 in), but most remain far smaller. Their most characteristic feature is the absence of the ventral fin, although this is shared by a few other pupfish. Despite their moderate to small size, they are important to local fisheries and a few species are farmed.
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.
Symphurus is a genus of fish in the family Cynoglossidae found in the Atlantic, Indian and Pacific Ocean. Most species mainly occur in relatively shallow water, including estuaries. Some species are also found in deeper water, including S. thermophilus that lives at hydrothermal vents. These species are distinguished by merged dorsal, caudal and anal fins, the absence of a lateral line and pectoral fins, and the presence of only one pelvic fin. They are sinistral flatfishes, meaning that as adults, their crania are asymmetrical, with both eyes on the left side. The largest species grows to about 32 cm (1 ft) long.
Omobranchus is a large genus of combtooth blennies found in the Pacific, Atlantic, and Indian oceans.
Odontesthes is a genus of Neotropical silversides. They are found in fresh, brackish and salt water habitats in the southern half of South America, as well as the offshore Juan Fernández and Falkland Islands. Additionally, O. bonariensis has been introduced to other continents.
Schizodon is a genus of headstander from South America. Though found widely in tropical freshwater habitats in the continent, the greatest species richness is in the Paraná–Paraguay–Uruguay river basin. They reach up to 40 cm (1.3 ft) in standard length. They are herbivorous, feeding on fruits, seeds, algae, macrophytes, leaves and roots.
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.
Odontostilbe is a genus of characins from tropical Central and South America, with 17 currently recognized species:
Pyrrhulina is a genus of freshwater fishes found in tropical South America. Several of these species are popular aquarium fish.
Austrolebias is a genus of killifish in the family Rivulidae. These annual killifish live in temporary pools, swamps and streams in the Río de la Plata, Patos–Mirim and Mamoré basins in South America.
Equulites is a genus of ponyfishes native to the Indian Ocean and the western Pacific Ocean. Analysis of mitochondrial DNA published in 2017 has suggested that Equulites elongates is in fact a species group made up of three species Equulites aethopos, Equulites elongates and Equulites popei.
Megaleporinus is a genus of fish in the family Anostomidae native to South America.
