I went on a goliath grouper dive last year near Palm Beach... amazing! Did you hear the booming noise they sometimes make?
Goliath groupers may be protogynous hermaphrodites. If you remember a previous column, this means they may begin life as females with some changing to males later in life. Other groupers often congregate in the hundreds or even thousands to reproduce. Goliath groupers form much smaller groups due to their low numbers, to over-fishing, and to their role as top predators. Divers have observed such spawning aggregations which peak around the full moon in late summer and early fall.
They are not shy, and prefer to mate in the middle of the day. Although courtship behavior was noted, actual mating has not been observed. It is said that the region forward of the pectoral fins in males becomes much lighter than the rest of the body. Females exhibit no color change. Courtship often involves the male inspecting the female's vent and nuzzling her (how sweet). Males also emit their booming sounds, sometimes as frequently as 3-4 per minute.
Star Thrower Educational Multimedia (S.T.E.M.) Dive Dry Column