Sweetlips (scientific name of Plectorhinchus) have big, fleshy lips and tend to live on coral reefs in the Indo-Pacific in small groups or pairs.

They will often associate with other fishes of similar species; several species of sweetlips sometimes swim together. They are usually seen in clusters in nooks and crannies or under overhangs. At nightfall, they venture from their shelters to seek out their bottom-dwelling invertebrate prey, such as bristleworms, shrimps, and small crabs.

Sweetlips colouring and patterning changes throughout their lives. For example, Plectorhinchus Polytaenia otherwise known as the Ribboned Sweetlips develops more stripes with age.

Juvenile sweetlips (seen in the picture above) generally look quite different from the adults, and often live solitary lives on shallower reef sections. Juveniles may be banded or spotted and are usually a completely different colour from the adults of their species. Small juveniles have an constant undulating swimming pattern, possibly mimicking poisonous flatworms as a means of predator avoidance. As they grow this behaviour gradually dissapears towards adulthood. When they are adults, they tend to shy away from divers, so can be difficult to obtain a good photo.

Here on Koh Tao, they are an important predator fish that feed on crustaceans and benthic (bottom dwelling) invertebrates. They are included in our Reef Check surveys as a key indicator of potential over fishing on our reefs.

Want to get involved in Reef Check surveys around the world ? Then sign up for our Reef Check Eco Diver Course and provide vital data for a global research database.