The fish has a compressed and fairly slender body, with a depth ranging from 2.3 to 2.9 times the standard length. The head profile is slightly to markedly concave above the eye, and the caudal fin is almost emarginate in specimens under 10 cm but becomes deeply forked in large adults. In terms of coloration, it is highly variable, depending on the fish’s mood. The coloration ranges from olive green or brown above to silvery below. There are 180 to several hundred pearly blue spots on the head and trunk, with 4–6 rows of close-set spots between the lateral line and the base of the anterior half of the dorsal fin. Frightened or injured fish may exhibit a mottled pattern with splotches of light and dark brown and whitish areas.