Parrotfish
Scientific name Scaridae
Parrotfish are some of the most important — and colourful — residents of Koh Tao’s reefs. Named for their beak-like teeth, which are fused into a strong dental plate, they scrape and bite algae from coral surfaces with a distinctive crunching sound you can sometimes hear underwater.
Their colours vary dramatically depending on species, age and life phase. Many parrotfish go through multiple colour transformations during their lifetime, shifting from muted juvenile tones to vibrant blues, greens and pinks as adults. Some species can even change sex as part of their natural life cycle.
As they graze, parrotfish bite off small pieces of coral rock, digest the algae within it, and excrete the remaining material as fine sand. In fact, much of the white sand found on tropical beaches originates from parrotfish digestion — making them literal reef sand producers.
At night, some species create a protective mucus cocoon around their body while they sleep, possibly helping mask their scent from predators.
Parrotfish are vital to reef health. By controlling algae growth, they prevent algae from overwhelming corals and allow reef systems to regenerate and thrive.
Find Parrotfish at...
Divemaster's tip
Listen carefully while hovering over the reef — the crunching sound of feeding parrotfish often gives away their location before you see them.
Look along shallow reef tops between 3–18 metres where algae growth is strongest. Early morning dives often provide the best light and activity.
What do they eat?
Parrotfish primarily feed on algae growing on coral and rocky surfaces.
By constantly grazing, they help maintain the delicate balance between coral and algae, playing one of the most crucial roles in keeping Koh Tao’s reefs healthy and resilient.
