Juveniles below about 8 cm are black with several horizontal white streaks. Larger ones up to about 20 cm uniformly dark, greenish brown, slowly becoming blue with age. Blue streak and patch extending behind the corner of the mouth of large males often quite brilliant. Uniformly yellowish-tan individuals rare. Caudal fin lunate in large terminal males. Scale rows on cheek 3. Median predorsal scales 3-4 (Ref. 37816). Males develop large hump on head and appear blunt-headed (Ref. 48636).