Fig. 15

Body deep; greatest depth contained 1.8 to 1.9 and caudal peduncle depth 11.0 to 13.9 times in SL; head length 2.9 to 3.1, predorsal distance 1.7 to 1.8 and caudal peduncle length 13.9 to 14.6 in SL; snout length 4.2 to 4.4, horizontal orbital diameter 3.0 to 3.7 and least interorbital width 3.4 to 4.5 in HL. Mouth terminal, dentary prognathous; premaxilla with 6, dentary with 7, maxilla with no teeth and palate with 4-7 teeth. Lateral line with 74-79 pored scales; transverse series above and below lateral line with 26-30 scale rows. Dorsal and pectoral fin with 15-17, pelvic fin with 7, anal fin with 32-36 and caudal fin with 19 rays. Ground color silvery; several dark-brown rounded blotches on body. Caudal and anal fins completely or partially black, including thin hyaline distal margin; remaining fins hyaline or yellowish, with few scattered black spots (Graça, Pavanelli, 2007).

Maximum standard length. 260.0 mm (Graça, Pavanelli, 2007).

Distribution. Paraná-Paraguay system.

Remarks. Serrasalmus marginatus is a non-native species from the upper rio Paraná. Its occurrence can be associated with the filling of the Itaipu Reservoir and the consequent inundation of the Sete Quedas Falls.