Blue Ring Angelfish

The blue ring angelfish takes its name from the bright blue ring behind the gill cover, at shoulder level. The orange–brown body of adults is decorated with several blue lines curving from the face toward the dorsal fin; the tail fin is pale whitish. Juveniles look completely different: they carry straight, thin white and light blue vertical lines on a dark navy background. In Koran angelfish juveniles these lines are curved, so the two species can be told apart this way while young.

All individuals are collected from the wild. Among the large angelfish it is one of the hardy species that switch easily to prepared foods; but it is a long-lived fish that reaches 45 cm, and the adult aquarium should be planned from the start.

It lives on coastal reefs of the Indo-West Pacific, down to at least 30 meters. Adults are often seen in pairs inside caves and under overhangs. Juveniles settle in very shallow rock and dead coral areas covered with short filamentous algae. In the wild it feeds on sponges and tunicates.

• Volume: at least 1000 liters and 200 cm in length for an adult.
• Water: salinity 1.023–1.026 specific gravity, pH 8.1–8.4, temperature 24–27°C. Strong filtration and a protein skimmer; regular water changes.
• Decor: a solid rock layout with caves; plenty of swimming space.
• Reef compatibility: not reef safe. It eats LPS and soft corals, zoanthids, tridacna clams and tube worms; a fish-only aquarium with live rock is the best setting.

Omnivorous. Offer angelfish foods containing sponge, frozen mysis, chopped mussels, shrimp and squid, dried seaweed and spirulina. It should be fed 2–3 times a day.

Once settled, it is bold and curious. It is aggressive toward its own species and other large angelfish; it may also act territorial toward fish added after it. For this reason it is usually one of the last fish added to the aquarium.

Good companions: in a large aquarium: tangs, foxface, large wrasses, calm triggerfish, large damsels, morays.

Avoid: other large angelfish, reefs with corals and tridacna clams, small and timid fish.

Kept as a single individual in the aquarium.

In the wild, pairs release pelagic eggs. It does not breed in home aquariums.

• Head and lateral line erosion (HLLE): common in large angelfish; a varied diet and good water quality prevent it.
• Marine white spot and velvet: quarantine is essential.
• High nitrate: shows itself as fading color and fin erosion.

The sexes cannot be reliably told apart externally.