Bryconops piracolina belongs to the subgenus Bryconops in having no teeth or rarely one tooth on the maxilla and a naked area on the cheek between the second and third infraorbitals. It is distinguished from all species of this subgenus by the pigmentation of the dorsal fin with a large black blotch extending from near the dorsal-fin base distally in contrast to the dorsal fins of congeneres that are slightly pigmented with scattered chromatophores. Bryconops piracolina furthermore is distinguished from all congeners, except B. inpai Knöppel, Junk & Géry, 1968, by possessing an entirely black adipose fin. It differs from B. inpai by its lack of humeral spots. It further differs from all species of the subgenus Bryconops , except for B. caudomaculatus (Günther, 1864), by having the last scales of the longitudinal series of scales that bears the lateral line series not pored beyond the end of the hypural plate. Bryconops piracolina differs from B. caudomaculatus by the number of pored lateral line scales (31-36, mean 34.6, n = 8, vs. 37-43, mean = 40.6, n = 101, respectively) (Ref. 87860).