Myloplus is a genus of freshwater fish in the family Serrasalmidae found in tropical and subtropical South America, where they inhabit rivers and streams (both slow and fast-flowing). They are primarily herbivores, but also take some animal matter. Depending on the exact species, they reach up to 16–56 cm (0.5–1.8 ft) in standard length. Adult males have a double-lobed anal fin and filamentous extensions on the dorsal fin, and both sexes (but especially males) can be brightly colored when breeding.

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