The semicircle angelfish is a narrow, oblong fish with a greenish-yellow or yellow-brown body covered in dark blue spots everywhere excepts its face and pectoral fins. It has a vivid blue margin on its fins, gill covers and eye. Juveniles are black with white, semi-circular lines radiating out from its tail - and from this pattern it gets its name. In adult semicircle angelfish, both the dorsal and anal fins are tailed by bright blue or yellow filaments.

Semicircle angelfish are solitary, inhabiting coral reefs in the Indian and Pacific Oceans. They hunt various small zooplankton. Juveniles are found in rock pools and in the waters of the Agulhas current.

All about angelfish

There are over 80 species of angelfish, 11 of which are found off southern Africa. Angelfish are underwater artworks – displaying spectacular colours and patterns. 

Most angelfish change their colours and patterns as they grow. Sexual dimorphism is common, males and females display different colours and markings – often so much so that they look like completely different fish!

Angelfish are not such angels – they have a secret weapon in the form of a sharp spine on each gill cover, which they use to defend themselves and to wedge themselves into cracks on the reef.


Species Facts

  • Colours and patterns change as the fish ages
  • Sharp spines on gill covers are used in defence
  • Grows up to 35cm.
  • Also known as a Koran angelfish, blue Koran angelfish or half-circle angelfish.