Yellowmask Surgeonfish

Photo: John Thorogood · CC BY-NC

Large schools of several hundred individuals patrol the water column above the reef in a characteristic undulating formation, descending periodically to graze patches of filamentous algae on the upper surfaces of the structures. They are important reef cleaners whose grazing behaviour maintains bare substrate for coral settlement and prevents algal domination that would otherwise smother the growing coral communities. The schools provide spectacular mid-water photography opportunities in the clear winter months.