Habitat: Marine. Inhabits reef areas, inshore bays and seagrass beds. Depth range 0 - 40 m. Natural History Notes: The large blue-headed adults males are far less numerous than those in the yellow color phase, but some usually can be seen swimming more actively and often higher above the reef than the little yellow ones. Not only the blue-headed individuals are sexually mature males, but also numerous yellow ones. Spawning by yellow fish of both sexes is a group affair, but when a blue-headed male is involved it is an act by a single pair of fish. Feeds on a great variety of small benthic animals and zooplankton. Yellow individuals occasionally pick parasites from other fishes. Often swims about reefs in schools. Spawn at midday throughout the year, sex reversal observed Characteristics: Three color phases. Adult : large males acquire the "bluehead" pattern and form (including long, pointed caudal fin lobes) : blue head followed by a black band, a pale band, another black band and a deep green to blue body. Initial phase : upper half of the head and body yellow, lower half white. Prominent black spot anteriorly on the dorsal fin. Can show in seconds either a broad dusky green midlateral stripe or a row of squarish blotches of the sane color. Young : black mid-lateral stripe, body below this bar white.