Is it possible to keep clownfish in social groups in the marine aquarium? Matt Pedersen advises.
In the wild, many clownfish live in social groups of a dominant female, a male, and one or more subordinate sexually immature male juveniles. Social pressure keeps the younger ones, not part of the pair, from maturing. They patiently wait their turn.
Images of clownfish in the wild reveal many species in groups, including Saddlebacks (A. polymnus), Common (A. ocellaris), Percula (A. percula), Black-footed (A. nigripes), Clark’s (A. clarkii), Pink skunk (A. perideriaon), and, I’m sure, others.
You may find big colonies of clownfish among large aggregations of anemones, with multiple pairs sharing adjacent spaces. However, I would never expect a group of a certain species to work, most notably the Maroon clown (Premnas biaculeatus).
Replicating the ‘pair plus’ social group in captivity doesn’t always work, but I’ve seen it work with ocellaris and clarkii, as well as having seen a massive group of Pink skunk (Amphiprion perideriaon) at Atlantis Marine World in Long Island, USA.
That doesn’t mean it will always work with these species. There is definite merit in adding all the fish at the same time as juveniles. If I tried adding a juvenile percula or ocellaris to a tank with a spawning pair, though, it would quickly killed.
Starting with juveniles all at the same time has risks and in more aggressive species may fail to work. I have a small isolated group of five black ocellaris (Amphiprion ocellaris ‘Darwin’) which are all siblings — the larger two being hatched a batch earlier. Even at three months, social pressure has created a runt that takes the brunt of aggression, so it hides, only showing up to feed.
I suspect that if I removed this fish the next one would suffer, and so forth, ultimately leaving me with just a pair.
In nature, clownfish living in groups will breed. In captivity it's generally felt that if you have more than two in a group breeding will be delayed because the fish will spend more time determining social rank. You may reduce the chances of this happening by selecting a larger, medium and one or more small fish — all from a group of juveniles.
Because size tends to correlate to social status and sexual function, judicious selection of fish may help reinforce the natural rankings each fish should occupy.
These fish may or may not breed. Things may go well for a while, but then, as the dominant pair matures, they may attempt to drive off all other fish. This may result in deaths, or a second splinter group which then forms its own breeding pair.
How all of this may occur depends on tank size, hosts and personalities. It is impossible to predict outcomes, so have spare tanks or breeder nets ready to isolate all extra fish if cohabitation doesn’t work!