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.