Koran Angelfish Juvenile (Pomacanthus semicirculatus)

The Juvenile Koran Angelfish (Pomacanthus semicirculatus), also known as the Semicircle Angelfish or Halfcircle Angelfish, is a spectacular marine fish prized for its distinctive markings and fascinating colour transformation as it matures. Its juvenile appearance features a deep blue-black body decorated with curved white and pale blue lines, creating an eye-catching pattern that makes it a standout addition to a large marine aquarium.

Native to the Indo-West Pacific, including the Red Sea, East Africa, Japan and Australia, the Koran Angelfish inhabits coastal reefs and rocky environments. Juveniles tend to be more secretive than adults, so providing plenty of live rock, caves and crevices will help your fish feel secure while offering opportunities to explore and graze.

As the Koran Angelfish grows, its appearance changes dramatically. The adult develops a greenish-brown body with blue-edged scales and distinctive blue edging on its fins. This transformation makes the species particularly interesting for aquarists who enjoy observing marine fish develop over time. However, its impressive adult size of around 35–40 cm means that a suitably large aquarium is essential from the outset.

A varied diet is important for maintaining the health and condition of this omnivorous species. Offer quality marine angelfish preparations containing sponge material, alongside frozen mysis shrimp, enriched brine shrimp, spirulina and marine algae. Feeding a varied diet in several smaller portions throughout the day can help support healthy growth.

The Koran Angelfish is not considered reef-safe. It may nip at corals, clam mantles and other sessile invertebrates, making a large fish-only or fish-only-with-live-rock aquarium the more suitable environment. It can also become territorial, particularly as it matures, so tankmates should be chosen carefully.

With its intricate juvenile markings and impressive adult appearance, the Koran Angelfish is an attractive choice for experienced marine aquarists able to provide ample swimming space, stable water conditions and a nutritious varied diet.

Care at a glance

• Scientific name: Pomacanthus semicirculatus

• Common names: Koran Angelfish, Semicircle Angelfish

• Adult size: Approximately 35–40 cm

• Origin: Indo-West Pacific

• Diet: Omnivore

• Temperament: Semi-aggressive; may become territorial

• Aquarium: Large, mature marine aquarium with plenty of live rock

• Reef compatibility: Not reef-safe

• Experience level: Intermediate to experienced

• Recommended setup: Fish-only or fish-only-with-live-rock aquarium

Plan for the fish’s adult size before purchasing, as juveniles grow into substantial angelfish that need considerable swimming space.