Okay, they are (like anemonefishes in General) 'protoandrous hermaphrodites', meaning they're all born male. Only the dominant individual gets to turn into a female in a given community, which revolves about a
host anemone. When the female dies, the next largest individual turns female and takes over.
There's more, but I wont take away the fun from the others here, haha.
I've read the above from so many sources, but I guess you can quote my favorite (because of its wonderful size)
A Field Guide to Anemonefishes and their Host Anemones, by Daphne Fautin and Gerald Allen.