Diagnosis: upper half of caudal fin always with alternating pattern of black and white to yellow stripes; lower half of caudal fin variable in males: uniformly violet (pale and sometimes almost transparent) across entire fin, or with many rows of red spots, or any combination of both; females always with an unmarked, clear to pale violet lower half of the caudal fin (Ref. 52307).

Description: males with elongated rays in dorsal, anal and pelvic fins, more so than females, and rays of upper portion of caudal fin may extend slightly, forming a small lappet; old males sometimes develop a small hump on their head (Ref. 52307).

Coloration: body grayish-brown in upper half and more turquoise in lower half of both sexes; dorsal fin with black margin followed by a white submargin that is always broader in females than in males; ripe females with an often extremely swollen, violet belly (Ref. 52307).