Anthias fish make up the subfamily Anthiinae of the family Serranidae (basses, basslets and groupers. They are mostly small and colorful, usually pink, orange and or yellow and thus quite popular within the ornamental fish trade. They can be seen swarming in most coral reef photography and film.
Anthias form complex social structures based on the number of males and females as well as their position on the reef itself. They occur in all tropical oceans and seas of the world and feed mainly on zooplankton. Anthias can shoal by the thousands. They also school within the shoals which is called “harems” which consists of one dominant, colorful male and anywhere from 2-12 females – who have their own hierarchy among them, as well as up to 2 sub-dominant males, often less brightly colored and non-territorial. Within the swarm of females, the territorial males perform acrobatic U-swim displays and vigorously defend and area of the reef and its associated harm.
Anthias are protogynous hermaphrodites. They are all born female and when a dominant male perishes, the largest female of the group will often change into a male to take its place. This may lead to fighting between the next largest male, who sees and opportunity to advance, and the largest female, whose hormones are surging with testosterone. Fighting can turn quite vicious in the limited confines of captivity.
There are seven species of anthias known to occur in coral reef ecosystems: Holanthias, Luzonichthys, Nemanthias, Plectranthias, Pseudanthias, Rabaulichthys and Serranocirrhitus. All seven species make it into the aquarium trade, however, Sea Goldies ( Pseudanthias) are the most encountered in the hobby.