Chaetodon ephippium. One of the most attractive species in this family/genus, having a yellowish-grey body with a large black, white edged patch on the upper aft of the body, wavy horizontal blue lines on the mid body, with the throat and pelvic fins bright yellow. Adults have a long trailing filament on the rear upper edge of the dorsal fin. There’s also some orange on the peduncle and trailing edge of the dorsal.