Sweetlips feed mainly on crustaceans, small fish and benthic invertebrates, typically hunting at night.
Their presence around Koh Tao indicates a healthy reef system with good structural shelter and abundant prey.
Sweetlips
Scientific name Haemulidae
Sweetlips are large, slow-moving reef fish known for their thick, fleshy lips and striking patterns. Around Koh Tao, the Harlequin Sweetlips and Oriental Sweetlips are the most recognisable species.
Adults often rest in small groups beneath overhangs, inside caves or along sheltered reef slopes between 8–25 metres. Their bold black, white and yellow patterns make them stand out beautifully against rocky backdrops.
Juveniles look completely different from adults — especially young Harlequin Sweetlips, which have exaggerated fins and perform a dramatic, wavy swimming motion. This behaviour mimics toxic flatworms, helping deter predators during their vulnerable early stage.
Sweetlips are relatively calm and tolerant of divers, often allowing close but respectful observation.
They play an important role in reef ecosystems as mid-level predators, feeding primarily at night.
Find Sweetlips at...
Divemaster's tip
Check beneath ledges and inside small caves during daytime dives. They often hover almost motionless in shaded areas.
If you see a juvenile performing exaggerated, ribbon-like movements near the reef, you’ve found one of the most fascinating mimicry behaviours on the reef.
