The peacock grouper lives in social groups consisting of a single dominant male and up to 12 females. Each group occupies a territory of up to 2,000 square metres, and this area is subdivided into smaller individual territories, each inhabited by one female (6). During courtship, the group come together at a specific site, the male swimming alongside each female in turn, aligning himself parallel and pressing slightly against the female’s flanks. Like many grouper species, the peacock grouper is able to change colour, and during courtship individuals may take on a dark colour pattern marked by a single vertical white band on the body (7). The peacock grouper may also change colour in aggressive confrontations with other grouper species (5), and its relatively large size means it is often the dominant individual in such encounters (6). Relatively little is known about reproduction in the peacock grouper (1), but like many other groupers it is likely to be a protogynous hermaphrodite, meaning individuals begin life as females, but change sex later in life to become males (2).
The peacock grouper feeds almost entirely on fish, although it will also take some crustaceans, such as shrimps or lobsters (8) (9). In some areas, most feeding takes place in the early morning and afternoon (5) (8), although in others it has also been recorded at night (9). The peacock grouper is typically an ambush predator, lying hidden among corals or in crevices, darting out to attack passing prey. While lying in wait, the fins may be folded against the body, and the grouper takes on a camouflaging colour pattern. Attacks may also occur when the grouper is swimming in midwater. However, a variety of other hunting techniques may also be used, including following another predator such as a moray eel or octopus and catching any prey which escapes from the first predator. The peacock grouper may also mingle with schools of other fish, hiding within the group and darting out to attack prey that passes close by (8).