Ageneiosus ucayalensis Castelnau, 1855 Fig. 18

Body elongated; greatest body depth contained 5.7 to 7.5 times in SL; head length 3.3 to 3.9, anal-fin base length 2.9 to 3.4 in SL; snout length 1.8 to 1.9, horizontal orbital diameter 9.5 to 12.9, least interorbital width 4.9 to 6.5 in HL; and orbital diameter 3.8 to 5.5 in interorbital width. Mouth terminal with dentigerous tooth plates in both premaxilla and dentary. Dorsal fin with I,6, pectoral fin with I,14-15, pelvic fin with I,7 and anal fin with 35-39 rays. Ground color greyish dorsally. Yellowish fins; distal margin of caudal fin black (Graça, Pavanelli, 2007).

Maximum standard length. 332.0 mm (Graça, Pavanelli, 2007).

Distribution. Amazon, lower rio Tocantins and río Corantijn basins and Paraná-Paraguay system (Eschmeyer et al., 2017).

Remarks. Ageneiosus ucayalensis 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.