The Koran Angelfish (Pomacanthus semicirculatus), also known as Blue Angelfish, Semicircle angelfish and Half-circled angelfish, is one of the most common and best known angelfishes.
It is native to the Indo-Pacific coral reefs and can reach about 40 cm in length. The juveniles have wide and narrow semicircular bands. When juveniles are smaller than 2 cm long, they have only three stripes. As they grow, the intervals of the stripes get wider until the body reaches 4 cm. At that stage, new stripes emerge between the original stripes. New lines are thin at first, but gradually get broader. When the body reaches 8 – 9 cm, an identical process is repeated.
As this angelfish matures, its blue background is replaced by golden brown with numerous blue specks on body and fins which are outlined in luminous blue. The pale markings on the caudal fin are regarded as being similar to the Arabic script used in the Koran, hence the unusual name of this species.
This majestic and solitary species is friendly and easily approached. Juveniles feed on small crustaceans, while adults feed on algae, sponges, sea squirts and invertebrates. Adults prefer outer reef walls and are often seen on shipwrecks.
- David Alderton – Encyclopedia of Aquarium & Pond Fish
- Dennis King – Reef Fishes & Corals: East Coast of Southern Africa
- Clifford Henry Taubes – Modeling Differential Equations in Biology