Forms schools in deep water exposed to current where it feeds upon zooplankton.  Hornless with a blue tail and brown trailing edge, dark edge of opercle and preopercle.  Body changes at will from blue-gray to olive brown with faint vertical splashes and yellow below.  Attains 30 inches.  Red Sea to Okinawa, Hawaii, French Polynesia, Clipperton, and Cocos Island.