It is distinguished from its similar species Nannostomus nigrotaeniatus by having the following characters: sexual dischormatism not developed, with males and females having red spots on the dorsal, anal and vertral fins and on the base of the caudal lobes (vs. well developed, with males having ruby spots on the dorsal, anal, ventral fins and on the base of the caudal lobes while females having hyaline fins); primary horizontal stripe is narrower and somewhat higher primary horizontal stripe not entirely covering the inferior part of the peduncle and extending onto the basal third or half of the three first lower caudal rays (vs. relatively wide and somewhat lower, covering the lower part of the peduncle and ends on the caudal peduncle or is only a little bit on the caudal fin in N. nigrotaeniatus ); and secondary horizontal stripe somewhat higher, extending to the base of the adipose fin (vs. relatively weakly developed, lower situated and extending to the end of the peduncle in N. nigrotaeniatus). The absence of red stripe between primary and secondary horizontal band also differs this species from another closely related species N. trifasciatus which has one red stripe, but this is only visible in living specimens) (Ref. 94659).