Angelfish

Angelfish are the most ornately patterned reef fish in the Indo-Pacific — emperor angelfish with electric-blue concentric arcs, regal angelfish with yellow-and-blue stripes, blue-girdled with green-and-yellow geometry. Juveniles look completely different from adults — emperor juveniles are dark blue with white concentric rings, a different pattern altogether.

They graze on sponges and tunicates (chemistry most other fish can't handle), pair-bond seasonally, and hold tight territories defended by both partners. The juvenile-to-adult colour shift happens around 8–15 cm body size.

Maldives, Andaman, Bali, Red Sea and Komodo all hold 5–10 species of angelfish on every dive. Look on coral-rubble slopes and along walls — they hover at reef-edge transitions and move slowly between sponge patches.