These fish 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 develops more stripes with age. Juvenile sweetlips 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 undulating swimming pattern, possibly mimicking poisonous flatworms as a means of predator avoidance.[4][5]
Juvenile Plectorhinchus lessonii off Taiwan
These are the currently recognized species in this genus:
Johnson, J.W.; Worthington Wilmer, J. (2015). "Plectorhinchus caeruleonothus, a new species of sweetlips (Perciformes: Haemulidae) from northern Australia and the resurrection of P. unicolor (Macleay, 1883), species previously confused with P. schotaf (Forsskål, 1775)". Zootaxa. 3985 (4): 491–522. doi:10.11646/zootaxa.3985.4.2. PMID26250161.
Damadi E, Moghaddam FY, Ghassemzadeh F, Ghanbarifardi M (2020) Plectorhinchus makranensis (Teleostei, Haemulidae), a new species of sweetlips from the Persian Gulf and the Gulf of Oman. ZooKeys 980: 141-154. https://doi.org/10.3897/zookeys.980.50934