Simpsonichthys is a genus of rivuline fishes, all species in the genus are restricted to freshwater habitats in eastern or central Brazil. Formerly one of the larger genera in the family, the subgenus Hypsolebias was elevated to full genus in 2011, thus removing many of the species formerly included in Simpsonichthys. Spectrolebias and Xenurolebias are valid genus and not subgeneras of Simpsonichthys.