Surgeonfish & Tangs

Surgeonfish are named for the scalpel-like spines at the base of their tail, flick the tail sideways and the spine flares out, drawing blood from any reef predator that closes too fast. The blue tang ('Dory'), powder-blue tang, palette tang, and unicornfish are all surgeonfish.

They're the algae lawnmowers of healthy reefs, schools of 50–200 graze coral surfaces in massed feeding waves, suppressing algal growth that would otherwise smother corals. Without surgeonfish, reefs slowly slime over and die.

Every reef destination: Maldives, Andaman, Bali, Red Sea, Komodo. Best photography: rising schools at reef edges during current dives, when whole groups feed in coordinated arcs.