Marine; reef-associated; depth range 0 - 180 m . Tropical; 26°C - 29°C ; 35°N - 33°S, 30°E - 128°W

Maturity: Lm ?  range ? - ? cm Max length : 70.0 cm FL male/unsexed; ; common length : 50.0 cm TL male/unsexed; ; max. reported age: 55 years

Dorsal spines (total): 6; Dorsal soft rays (total): 27 - 30; Anal spines: 2; Anal soft rays: 27 - 30. This species is characterized by the following: body depth vary from about 2.0 in SL (in subadults) to 2.4-2.6 (adults) in SL; with a tapering, bony, horn on forehead of adults projecting anteriorly at level of eye but not extending in front of mouth (horn first as a bump on forehead at a length of about 12 cm); dorsal profile from snout to horn straight, angle of about 45°; 2 peduncular plates with well-developed forward-curving knife-like spines; emarginate caudal fin when young, truncate with filamentous lobes in adult; males apparently with longer horn, larger peduncular keels and longer caudal filaments than females of the same size; body yellowish to olivaceous gray dorsally, paler ventrally, with blue peduncular plates and keel spines; lips whitish or blue; blue area is sometimes present around pectoral fin; dorsal and anal fins yellowish with narrow blue margins; caudal fin orangish basally, shading to gray, with a broad, pale greenish posterior border and caudal filaments are edged in blue; one transient color phase is a blotchy pale greenish zone below the spinous portion of dorsal fin that narrows and ends beneath the pectoral fin . Body shape (shape guide): short and / or deep;  Cross section: compressed.