Harlequin rasbora of a harlequin. The harlequin rasbora is a fish that has an approximately lozenge-shaped body, whose basal colour from the head to the caudal peduncle is an orange-pink, the exact hue varying depending upon such factors as water conditions and the original population from which the fish was obtained. The posterior half of the body is overlaid with a large, roughly triangular black marking, that tapers toward the terminal end of the caudal peduncle, and begins approximately below the midpoint of the attachment of the dorsal fin (commonly called a "black wedge"). In common with all cyprinids, the articulation of
Breitensteinia in five to six longitudinal rows on each side, a dorsal profile rising evenly but not steeply from the tip of snout to the origin of dorsal fin and then sloping gently ventrally from there to the caudal peduncle, a horizontal ventral profile to the origin of the anal fin and then rising to the caudal peduncle, a dorsal fin origin nearer to the tip of the snout than caudal flexure, and a truncate caudal fin. "B. hypselurus" has a smooth posterior edge to its dorsal fin spine, relatively tall neural spines on the caudal vertebrae, a shorter caudal peduncle,