Angelfish
Scientific name Pomacanthidae
Angelfish are among the most colourful and elegant residents of the reef. With their laterally compressed bodies, extended dorsal and anal fins, and striking colour patterns, they bring movement and vibrancy to Koh Tao’s coral gardens.
Two of the most recognisable species locally are the Blue Ring Angelfish (Pomacanthus annularis) and the Emperor Angelfish (Pomacanthus imperator). Both species undergo dramatic colour changes as they mature. Juveniles display hypnotic circular blue and white patterns, while adults develop bold stripes, yellows and electric blues.
Angelfish are often seen cruising slowly along reef walls and coral heads, carefully picking at surfaces. They are territorial and usually found alone or in pairs rather than in large schools. Their confident swimming style and bright colours make them a favourite for underwater photographers.
Ecologically, angelfish play an important role by feeding on sponges and algae, helping prevent any one organism from dominating the reef ecosystem. Their presence is a good sign of reef health and structural complexity.
Find Angelfish at...
Divemaster's tip
Look along coral heads and reef slopes between 5–25 metres. Juveniles are often found in sheltered areas with plenty of cover, while adults patrol more open reef structures.
Move slowly and approach from the side rather than above to avoid startling them — angelfish are curious but cautious.
What do they eat?
Angelfish primarily feed on sponges, algae and small invertebrates.
Their specialised mouthparts allow them to graze carefully along reef surfaces, playing a subtle but important role in maintaining the balance of coral ecosystems around Koh Tao.
