Basic color is dark brown or black. Dorsal fin has rows and stripes of white on black. Large males have iridescent blue and ebony markings and a fatty hump in front of the dorsal fin. Females may have indistinct vertical barings. The topmost ray of the caudal fin is much elongated in adults and may be tri-lobed. A sharp spine is located near the posterior margin of gill cover. The lower jaw sticks out beyond their upper lip. Tail fin is rounded and larger fish may possess an elongated filament that extends beyond the tail.