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All Sea Goldies start life as females. Females are induced tot change by removal of the male from the social group. The largest, most dominant female in the school becomes a male. Large schools, with one male and many females, live as harems on reefs. Males will drive off any other males, and females will create a pecking order by beating up subordinates.

Females are orange tot yellow. Males are purplish with a yellow spot on the body scales and a large purplish blotch on  the pectoral fin. Males also have a greatly elongated thrid dorsal fin spine and a caudal fin with longer lobes than females.

(Sources: pets.thenest.com and australianmuseum.net.au)