Chaetodontoplus mesoleucus

The vermiculated angelfish (*Chaetodontoplus mesoleucus*) is a marine ray-finned fish from the family Pomacanthidae, found across the Indo-West Pacific. Its face is yellow with blue lips, and a black vertical band runs through the eye. Behind the head, the body is a cinereous color that transitions into a larger black area covered in yellow speckles. The caudal fin is yellow, while the dorsal and anal fins have vivid blue margins; the pelvic fins are white. The dorsal fin has 12 spines and 17–18 soft rays, and the anal fin has 3 spines and 17–18 soft rays. This species reaches a maximum total length of 18 centimeters (7.1 inches).

Its range extends from southern Japan south through Indonesia, west to the Mentawai Islands, east to the Bird’s Head Peninsula of New Guinea, and south to northern Australia. In Australia, it occurs from the Kimberley Region reefs south to Varanus Island, and at Ashmore Reef in the Timor Sea. It lives at depths of 1 to 30 meters (3.3 to 98.4 feet), on continental shelf reefs with rich coral growth in silty inner coastal reefs and lagoons, and is rare around oceanic islands. The diet consists of sponges, tunicates, and filamentous algae. It is usually seen in small groups and hides among coral when alarmed. Like all angelfish, it is a protogynous hermaphrodite—all individuals start as females, and the dominant ones change to males.

The species was first formally described in 1787 by German naturalist Marcus Elieser Bloch, with the type locality given as Japan. The specific name *mesoleucus* combines *mesos* (middle) and *leucus* (white), possibly referring to how the white front half of the body shades into the black rear half at the flanks. *Chaetodontoplus poliourus* was once considered the same species but differs in having a yellow-margined grey caudal fin, yellow pelvic fins, and a paler yellow dorsal fin margin. The vermiculated angelfish is exported for aquariums and is one of the most popular aquarium species.