I read somewhere that flame angles can change sex, some eals also can change sex. Also some clows share genetic links with Damselfish and there for fall into the same classification in some books that is. Fish changing sex is posible in many species I believe from some of the reading I have done over the years. as snails can hold sperm so can sertain fish that are fertilized internaly and are either brooders or live bearers, this is mainly in fresh water fish.

Bill