Piaractus mesopotamicus

Pacú (Piaractus mesopotamicus), pez chato ("flat fish"), mbiraí, or piraí, is a South American ray-finned fish that is endemic to the Paraguay-Paraná River basin, though it has been introduced by aquaculture activities in a wider area.
P. mesopotamicus is a robust fish, with ovoid shape, flattened laterally. Its colour is dark grey to silver, with a white belly and a yellow breast, and the laterals have small darker spots.
This fish is an omnivore. Young individuals usually feed on micro-crustaceans, but adults choose insects and plants, as well as nuts and seeds that fall from trees in flooded forests.
References

"Piaractus mesopotamicus". Integrated Taxonomic Information System. Retrieved 24 January 2006. 
Froese, Rainer and Pauly, Daniel, eds. (2005). "Piaractus mesopotamicus" in FishBase. 10 2005 version.
Migratory fishes of the Upper Paraná River basin, Brazil. A. A. Agostinho,
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