Myleus is a genus of serrasalmids from South America, where found in the Amazon, Orinoco and São Francisco basins, as well as the river basin of the Guiana Shield.

[1] They are found in rivers with moderately or fast-flowing water, including rapids.

[2] They are primarily herbivores, but also take some animal matter.

[2] Depending on the exact species, they reach up to 12–42 cm (0.4–1.4 ft) in standard length, and the adult males have a double-lobed anal fin and filamentous extensions on the dorsal fin.

[2] Their strong teeth means that larger individuals can inflict severe bites on humans.