Chaetodon lunula can reach a length of 20 cm (nearly 8 in).[2] These large butterflyfishes have an oval outline, with a pattern of ascending oblique reddish stripes on the flanks and black and white bands over the face and eyes, similar to the "raccoon" mask (hence the common name). They show a black spot on the caudal peduncle and oblique yellow stripes behind the head.[6] They have 10-14 dorsal spines and 3 anal spines