Ossubtus

thumb | right | alt=Adults of Ossubtus xinguense: GEA 1973, (a) male, 202.7 mm SL; (b) female, 168.5 mm SL. Brazil, Rio Xingu, Volta Grande. | Adults of Ossubtus xinguense: GEA 1973, (a) male, 202.7 mm SL; (b) female, 168.5 mm SL. Brazil, Rio Xingu, Volta Grande. Ossubtus is a genus of fish in the family Serrasalmidae. It contains a single species, Ossubtus xinguense, the parrot pacu or eaglebeak pacu, The species is endemic to rapids in the Xingu River basin in the Brazilian Amazon. This vulnerable species is primarily a herbivore.

==Description== The body of Ossubtus xinguense is ovoid in shape. The profile of the snout is blunt. In young fish, the mouth is terminal (pointing forward); however, as the fish grows, the mouth turns downward and becomes strictly ventral in individuals longer than . This gives the mouth a beak-like appearance. It reaches up to in total length and about in weight.