The dusky grouper is a protogynous hermaphrodite, meaning that it matures as a female but later develops into a male as it grows larger and older (5). Sexual maturity is attained fairly late, when females are around five years of age, while sex reversal of females into males takes place between the 9th and 16th year, peaking at 12 (1) (5). The grouper usually leads a solitary and relatively sedentary life, except during the breeding season when small clusters of a few tens of individuals form at specific spawning sites (1) (5). The spawning season in the Mediterranean is from June to September (5), mating is polygynous and aggregations generally have a female bias of around seven females to each male (1) (5). During this period, dominant males establish territories and demonstrate strong territorial behaviour, acting aggressively towards neighbouring males and smaller females (1) (7). The maximum reported age of a dusky grouper was about 50 years (2).
Diet consists of crustaceans, molluscs and fish, with diet varying with body size (8). While younger, smaller groupers feed primarily on crustaceans, larger individuals feed on a greater proportion of fish, with the majority being reef-associated species (8) (2).