Whip butterfly fish. Common name: Black-rumped butterfly. The fourth ray of the dorsal fin is extended in a filamentous shape. There is a large oval blue-black spot on the back and upper part of the body. The lower edge of the spot has a wide white edge and the rear edge is orange-red. There are 6-7 blue longitudinal bands on the side of the body. Body length 20 cm. Distribution areas: Xisha Islands, Nansha Islands, Taiwan waters, Indian Ocean and Pacific tropical waters.
