Catostomus utawana is distinguished from C. commersonii by the following characters: eye diameter twice or less into snout length (vs. more than twice into snout length); caudal peduncle depth at terminus more than twice into anal-fin length (vs. less than twice into anal-fin length for a small individual); dorsolateral scales of with radii in the dorsal ventral, anterior, and posterior fields (vs. scales with radii in the anterior and posterior fields); individuals rarely exceed 200 mm SL (vs. non-stunted adults of much greater lengths for C. commersonii). In breeding condition, this species is distinguished from C. commersonii by the following characters: pearl organs on anal and caudal fins and on scales found near the anal fin and ventral areas of the caudal peduncle on females (vs. none); pearl organs on nearly every scale and on all fins for males (vs. pearl organs on anal fin, caudal fin, and scales between); males with gold stripe above a dark mid-lateral stripe on both sides, and a gold spot above each eye (vs. a longitudinal white stripe that turns vertically to cross the occipital region or the snout, and no spots dorsal to their eyes); females without stripes (vs. a yellow stripe that resembles the white stripe of male C. commersonii); breeding males and females no red coloration (vs. a scarlet stripe on both male and female) (Ref. 83995).