Distinguished from all other species of Melanorivulus, except M. kayapo, by having a colour pattern of flank in males consisting of irregular horizontal rows of red dots arranged to form a red reticulate pattern on the posterior part of flank, including canal peduncle region (vs. never a similar colour pattern; usually oblique red bars on the flank, reticulated areas when present are symmetrical and derived from overlapping bars). M. kunzei is distinguished from by having fewer caudal-fin rays (29-30 vs. 32-34), more neuromasts in the infraorbital series (1 + 11 + 1 vs. 1 + 7-9 + 1), and by the presence of dark grey dots on the subdistal portion of dorsal fin and middle of caudal fin in males (vs. absence) and small red spots on the caudal fin in males (vs. horizontally elongated red spots)(Ref. 92338).