25.0 cm SL (male/unsexed; (Ref. 76907))
Leporinus amazonicus belongs to the friderici-group, as defined by Géry (1977) andGaravello (1979). It differs from most of congeners (except L. fasciatus, L. affinis and L. y-ophorus) by the high lateral line scale count (4547 versus 43 or fewer), and from these species by the color pattern (brownish- grey with one small and elongated dark blotch on the flanks in L. amazonicus vs. yellow ground color withseveral single or divided vertical dark bars on the side in the others). Leporinus amazonicus is morphologically similar to the slender bodied species L. cylindriformis Borodin, 1929 and L. brunneus Myers, 1950, but differs from them by the higher lateral line scale count (4547 versus 4143 in L. cylindriformis and 3642 in L. brunneus) and by a different color pattern (lateral blotch occupying 24 horizontal scales in L. amazonicus versus 57 in L. cylindriformis, and absence of well defined blotches on the body sides in L. brunneus) (Ref. 76907).