Anterior spines of first dorsal fin much higher than those mid-way, giving the fin a strongly concave outline. Interpelvic process small and bifid. Body naked except for corselet and lateral line. Swim bladder absent. A large rounded protuberances on 31st and 32nd vertebrae. Color is generally iridescent blue with black dorsal markings composed of 3 to 5 horizontal stripes. Also with variable black or dark gray spots above the pelvic fins. Occasionally with extensive longitudinal stripes of light gray on belly; some individuals have few or no belly markings.