Pomacanthus annularis is a large, deep-bodied angelfish distributed across the Indo-West Pacific, from the East African coast through Indonesia and New Guinea to New Caledonia and north to southern Japan. Adults wear a tan to golden-brown body crossed by sweeping sapphire-blue stripes, finished with a pale tail, blue facial markings, and the distinctive blue ring above the gill cover that gives the species its name. Juveniles look nothing like their parents, appearing dark brown to blue-black with curved white and cyan vertical bands that reorganize entirely as the fish matures. Adults reach roughly 17 inches, with reports to about 18 inches in the wild.

On the reef, this species occupies coastal habitat where adults are frequently seen in pairs sheltering inside caves, while juveniles remain in shallow inshore zones among rock and dead coral grown over with filamentous algae. A mature, well-filtered aquarium of at least 220 gallons suits a single adult, and that volume should be arranged to provide both extensive open swimming lanes and substantial rockwork riddled with caves, crevices, and visual barriers. Grazing surfaces on established live rock are valuable, as is brisk water movement and strong oxygenation. Cramped quarters tend to sharpen this angelfish's territorial streak, so err toward more length and footprint rather than less.