Biology

Typically found hovering just above the bottom (2), this large grouper is one of the major predators within its coral reef habitat (3), feeding on a range of large fish, including other grouper species and crustaceans. Its tendency to feed on large fish explains why high concentrations of ciguatoxin may be found in this species (1). Like many groupers, this species has a fascinating life history. All blacksaddled groupers begin life as a female, and then as the animal ages, based on internal or external triggers, it shifts sex to become a male animal, a system known as protogynous hermaphroditism (3). Most groupers are solitary fish, except when it comes to spawning (3), when small groups or larger aggregations form to release large quantities of eggs into the surrounding water (1). The eggs are fertilised by sperm released by males into the water, and after a period, the round, floating eggs hatch to reveal a tiny larva. The blacksaddled grouper is a fairly fast-growing species, with females reaching maturity in less than three years (1). Groupers typically spawn as a female for one or more years, before changing sex and then functioning as a male (3).