Morphology: Dorsal spines (total): 0 - 0; Dorsal soft rays (total): 19 - 21; Anal spines: 0 - 0; Anal soft rays: 23 - 24. The filamentous last dorsal fin ray distinguishes this species from all other western Atlantic clupeoids except Dorosoma, which has an inferior mouth (Ref. 188). Otherwise, superficially resembles species of Sardinella (but i 8 pelvic fin rays in western Atlantic species, cf. i 7 in Opisthonema) and Harengula (but small toothed hypomaxilla in upper jaw) (Ref. 188). Lower gill rakers stable at 28 to 46 after 8 cm (Ref. 188). Silvery, with a bluish or greenish back, 6-7 lengthwise dark streaks on side. Dark spot above opercle, larger dark spot behind opercle, usually with a row of dark spots behind it. Lower profile deeply curved. Head pointed (Ref. 7251).

Max size: 38 cm TL (male/unsexed; Ref. 5217); max. published weight: 375 g (Ref. 5217)