Nothobranchius is a genus of small, freshwater killifish, classified in either the family Nothobranchiidae or a more inclusive Aplocheilidae in the order Cyprinodontiformes. There are many species: as of 2018 there are more than 70 species, many with very small distributions. They are primarily native to East Africa from Sudan to northern South Africa, but half a dozen species are found in the upper Congo River Basin and two species are from west-central Africa; the greatest species richness is in Tanzania.
Rivulus is a genus of small freshwater fish in the Cyprinodontiformes family Rivulidae. It was traditionally considered to be the largest genus in its family; however, the genus's size is currently in dispute. Wilson J. E. Costa split this genus into several new genera in 2004 and 2011, leaving only a few Greater Antillean species in Rivulus itself. Despite being moved to other genera, some of the species retain the common name "rivulus", like the well-known mangrove rivulus. Shortly after the review by Costa, another review authored by J.H. Huber refuted the split, moving the proposed genera back in Rivulus and again making the genus the largest in the family Aplocheilidae.
Aphyosemion is a genus of African rivulines endemic as the name indicates to Africa. Many 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.
Hypsolebias is a genus of small fish in the family Rivulidae that are endemic the Caatinga, Cerrado and nearby regions in Brazil. The greatest richness is in the São Francisco River basin, but there are also species in the Tocantins, Jequitinhonha and Jaguaribe systems, as well as smaller river basins in northeastern Brazil. Like their relatives, Hypsolebias are annual killifish. The short-lived adults inhabit temporary waters like rain pools, laying their eggs in the bottom. As their habitat dries up the adults die, but the eggs survive and hatch when the water returns in the next season.
Maratecoara is a genus of killifish in the family Rivulidae. These annual killifish are endemic to seasonal pools, swamps and lagoons in the upper Araguaia–Tocantins and middle Xingu river basins in Brazil. Most are from savanna regions, but M. gesmonei is from the Amazon rainforest.
Melanorivulus is a genus of chinease freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon, Tocantins–Araguaia and São Francisco basins in Brazil, but a few members of this genus range west into Bolivia, south into Paraguay and Argentina, and east to Parnaíba and Sergipe in northeastern Brazil. Only M. schuncki occurs north of the Amazon River. They inhabit shallow waters, generally 5–30 cm (2–12 in) deep, at the margins of streams in open or fairly open habitats like the Cerrado or Cerrado–Amazon transition. Many have tiny ranges and are seriously threatened.
Anablepsoides is a genus of killifish in the family Rivulidae native to tropical South America and the Lesser Antilles. The majority are from the Amazon and Orinoco basins, as well as freshwater systems in the Guiana Shield, but a few species are from northern Venezuela, northeastern Brazil and the Lesser Antilles. Although largely restricted to lowlands, a few species occur in the lower East Andean foothills. They are mostly found in shallow fresh water swamps, streams, edges of rivers, ponds and pools, but a few may occur in brackish estuaries. They are able to jump over land and breathe air for short periods, allowing them to access isolated waters inhabited by few or no other fish. Several Anablepsoides species have small distributions and some are seriously threatened by habitat loss; the entire known range of A. xinguensis is in the area flooded by the Belo Monte Dam.
Laimosemion is a genus of fish in the family Rivulidae from the Amazon basin and basins in the Guiana Shield in tropical South America. They mostly inhabit small streams, creeks, swamps and pools in lowlands, but locally occur to an altitude of 1,300 m (4,300 ft).
Moema is a genus of fish in the family Rivulidae. These annual killifish are mostly restricted to the Amazon basin in Bolivia, Brazil and Peru, but a few inhabit the upper Essequibo basin in Guyana, upper Orinoco basin in Venezuela and upper Paraguay basin in Brazil. They inhabit temporary waters, such as swamps or ponds, in primary forests. Once the water disappears, the adults die, but the eggs that have been laid in the bottom remain, only hatching after 3–10 months when the water returns. They rapidly reach adult size, but generally only live a few months after hatching, although captives can live longer.
Neofundulus is a genus of fish in the family Rivulidae. These annual killifish are endemic to the Paraguay, Guaporé, Mamoré and São Francisco basins in Argentina, Bolivia, Brazil and Paraguay. They inhabit temporary waters, such as swamps or ponds, that typically are located in open habitats like grassland. Once the water disappears, the adults die, but the eggs that have been laid in the bottom remain, only hatching after several months when the water returns.
Pituna is a genus of fish in the family Rivulidae. These annual killifish are endemic to seasonal pools, swamps and lagoons in the Araguaia–Tocantins, Xingu, uppermost Paraná and Paranaíba river basins in Brazil. Most are from savanna regions, but P. xinguensis is from the Amazon rainforest.
Plesiolebias is a genus of fish in the family Rivulidae. These annual killifish are endemic to seasonal pools, swamps and lagoons in the Araguaia–Tocantins, Xingu, and uppermost Paraguay (Pantanal) river basins in Brazil.
Pterolebias is a genus of killifish from the family Rivulidae which are native to temporary swamps and ponds in South America. It includes two groups, which sometimes are regarded as separate genera: Pterolebias from the southern Amazon and Paraguay river basins, and Gnatholebias from the Orinoco river basin.
Rachovia is a genus of killifish from the family Rivulidae the species of which are endemic to the Orinoco, Maracaibo and Magdalena basins in Colombia and Venezuela, where they live in small temporary waters like ponds. They are small annual killifish that reach up to 6 cm (2.4 in) in total length. The name of this genus honours the German aquarist Arthur Rachow (1884-1960) who sent fish specimens to George S. Myers.
Simpsonichthys is a genus of killifish from the family Rivulidae the species of which are endemic to temporary freshwater habitats like ponds in the upper Paraná, upper Araguaia, upper Jequitinhonha and São Francisco basins on the central Brazilian Plateau. They are small annual killifish that reach up to 5.5 cm (2.2 in) in standard length.
Stenolebias is a genus of fish in the family Rivulidae. These relatively rare annual killifish are endemic to seasonal waters in the Pantanal in Brazil.
Trigonectes is a genus of fish in the family Rivulidae. These annual killifish are endemic to the Paraguay, upper Madeira and Tocantins basins in far northern Argentina, Bolivia, central Brazil and western Paraguay. They inhabit seasonal swamp, pools and similar habitats in open regions. Once the water disappears, the adults die, but the eggs that have been laid in the bottom remain, only hatching after several months when the water returns.
Xenurolebias is a genus of fish in the family Rivulidae. These annual killifish are endemic to temporary pools in the Atlantic forest near the coast in southeast Bahia and Espírito Santo, Brazil.
Spectrolebias is a genus of killifish in the family Rivulidae. These annual killifish are endemic to seasonal waters in the Paraguay, Tocantins–Araguaia, Xingu and Mamoré–Grande basins in Bolivia, Brazil and Paraguay. Each species generally has a small distribution and some are seriously threatened by habitat loss; the entire known range of S. reticulatus is in the area flooded by the Belo Monte Dam.
