Nothobranchius is a genus of small, freshwater annual fish from in the family Nothobranchiidae which was long included in the Aplocheilidae. They are mainly found in East Africa from Sudan to northern South Africa, but half a dozen species are found in the upper Congo River Basin and two species (N. rubroreticulatus and N. thierryi) are from west-central Africa. The greatest species richness is in Tanzania. Many species have very small distributions.