Mylesinus is a genus of serrasalmids from South America, where found in the eastern Amazon, Essequibo and Orinoco basins.

They are rheophilic, typically found at rapids and mainly feed on Podostemaceae plants.

[1][2] Because of their habitat preference, they are threatened by the building of dams.

[2] They reach up to 35 cm (1.15 ft) in standard length,[3] and the adult males have a double-lobed anal fin and several filamentous extensions on the dorsal fin.

This Characiformes-related article is a stub.