Fairly common along current-swept dropoffs where it feeds upon zooplankton.  Color changes at will from dark gray-brown to blue-gray, with a black spot at rear base of dorsal fin, and a black patch below pectoral fin base.  The white tail is present except in Hawai'i.  Attains 11 inches.  East Africa to Okinawa, Hawai'i, and French Polynesia.