Piaractus mesopotamicus, the small-scaled pacu, Paraná River pacu or simply pacu (a name shared with other species), is a South American ray-finned fish that is native to the Paraguay-Paraná River basin,[3][4] but it has been introduced by aquaculture activities in a wider area.[5] In its native range it is also known as the pacú chato, pez chato ("flat fish") or mbiraí-piraí.[6]
Piaractus 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.[3] It reaches up to 62 cm (2.03 ft) in length[5] and 20 kg (44 lb) in weight.[3] The other member of its genus, P. brachypomus, can be distinguished by its larger scale-size[7] and the lower number of lateral scales (less than 110).[8]
Piaractus mesopotamicus is an omnivore.[5] Young individuals usually feed on micro-crustaceans, while adults feed on plant material and insects.[5] Main food items for adults are nuts and seeds that fall from trees in flooded forests.[3] It tolerates water temperatures between 15 and 35 °C (59–95 °F), but stops feeding when it falls below 18 °C (64 °F).[5]
^Nico, L.; and B. Loftus (7 October 2012). Piaractus mesopotamicus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. Retrieved 13 March 2017.
^ abcdeA. A. Agostinho, L. C. Gomes, H. I. Suzuki, H. Ferreira Júlio Jr: Migratory fishes of the Upper Paraná River basin, Brazil. Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (Nupelia). Universidade Estadual de Maringá. Maringá, Paraná, Brazil.
^Nico, L.; P. Fuller; and M. Neilson (22 October 2013). Piaractus brachypomus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. Retrieved 2 March 2017.
