All species of the genus Sinamia (Sinamiidae, Amiiformes) are reviewed on the basis of the examination of the holotypes, paratypes, other specimens, and original descriptions of each species. Diagnoses are provided for all species. Phylogenetic analysis supports the monophyly of the family Sinamiidae and demonstrates that the long dorsal fin base in Sinamia and Amia is a matter of convergence. It is considered that the species having a long dorsal fin base lived in still water with vegetation, like Amia calva, while the species having a short dorsal fin base probably lived in the open water.