Semicircle Angelfish

The Semicircle Angelfish (Pomacanthus semicirculatus), also called the zebra angelfish, is a large marine angelfish of the Indo-Pacific. Adults are greenish-brown with fine blue speckling, blue-edged fins, and blue lines around the face, while juveniles are dark blue with striking white and blue semicircular bars that give the species its name. Like other large angelfish it feeds on sponges, algae, and invertebrates and needs plenty of reef structure. Its dramatic change from banded juvenile to speckled adult is typical of the genus Pomacanthus.

Identify the Semicircle Angelfish by:

• Adults: greenish-brown body with fine blue speckles, blue-edged dorsal and anal fins, and blue facial lines.
• Juveniles: dark blue with white and blue curved (semicircular) bars.
• Large, deep angelfish body, ~30-40 cm.

The curved bars on juveniles and the blue-speckled greenish adults distinguish it from other Pomacanthus angelfish.

Semicircle Angelfish inhabit coral and rocky reefs, lagoons, and sheltered slopes from about 1 to 40 m across the tropical Indo-Pacific, from the Red Sea and East Africa to the western Pacific. They favour reefs with caves, ledges, and rich growth that provide shelter, with juveniles often in shallow, protected areas.

Semicircle Angelfish are diurnal omnivores, feeding on sponges, tunicates, algae, and small invertebrates. Adults are usually solitary or paired and can be shy, staying near caves and structure. As protogynous hermaphrodites, juveniles differ markedly from adults, and dominant fish become males; pairs spawn by ascending into the water column to release eggs.