Piaractus mesopotamicus (Holmberg, 1887) Fig. 15 Body deep; greatest depth contained 1.5 to 2.0 and caudal peduncle depth 8.8 to 8.9 times in SL; head length 2.7 to 4.2, predorsal distance 1.6 to 1.7 and caudal peduncle length 8.8 to 9.4 in SL; snout length 2.9 to 3.3, horizontal orbital diameter 5.2 to 5.5 and least interorbital width 1.9 to 2.1 in HL. Mouth terminal; inner row of premaxilla with 2, outer row with 6-8; inner dentary row with 2, outer with 6; maxilla with 1 or 2 teeth. Lateral line complete, with 107-119 pored scales; transverse series above lateral line with 49-54 scale rows and below with 50-55 scale rows. Ventral keel with 52-54 simple spines, plus 7 pairs of spines. Dorsal fin with 15 or 16, pectoral fin with 14-17, pelvic fin with 8 or 9, anal fin with 23- 25, and caudal fin with 19 rays. Ground color greyish, darker dorsally. Dorsal and pectoral fins dark-grey; pelvic anal and caudal fins yellowish-orange (Graça, Pavanelli, 2007). Maximum standard length. 533.0 mm (Graça, Pavanelli, 2007). Distribution. Paraná-Paraguay system.

Published as part of Ota, Renata Rúbia, Deprá, Gabriel de Carvalho, Graça, Weferson Júnio da & Pavanelli, Carla Simone, 2018, Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated, pp. 1-111 in Neotropical Ichthyology 16 (2) on page 53, DOI: 10.1590/1982-0224-20170094, http://zenodo.org/record/3678395

{"references": ["Pavanelli CS, Graca WJ, Zawadzki CH, Britski HA, Vidotti AP, Avelino GS, Verissimo S. Fishes from the Corumba Reservoir, Paranaiba River drainage, upper rio Parana basin, State of Goias, Brazil. Check List. 2007; 3 (1): 58 - 64."]}