This species belonging to the N. maculatus species group have scales associated with the postorbital spot on the cheek and show breeding behavior in which males guard clumps of eggs in crevices under rocks (vs. having a completely unscaled cheek and burying clumps of eggs in substrate with no subsequent care in all other species of Nothonotus<>). Within the species group, N. starnesi and N. sanguifluus differs from all other species on the basis of pigmentation patterns, males have red pigmentation covering a high proportion of all the median fins (vs. green median fins in N. wapiti and N. microlepidus; greenish blue anal and pelvic fins in N. vulneratus and N. maculatus); and, the presence of a suborbital bar (vs. absent in Nothonotus aquali). Male nuptial coloration of N. starnesi tends to have less-pronounced darkening of pigment at the base of the first three interradial membranes of the spinous dorsal fin and in the pelvic fins, has much more discrete and contrasting vermiculation on the head and cheek, and has more red in the pectoral fins when compared with N. sanguifluus. In addition, N. starnesi have lower mean numbers for pored lateral line scales, scales below the lateral line, and scales in the most ventral row of the opercle (Ref. 93269).