Originally Posted by woody390
To my knowledge clownfish don't change gender. They are born without gender then develop into male and female on Dominance but once male/ female they not change again.
+1. There are 3 classes of sex in clowns. Juvenile (unsexed) male, then female. Once they move up from one, they cant switch back. In the wild, depending on the number, their would be one or two females, then several males to mate with them. Alot of hobbyists have experienced problems adjusting clown pairs because they were too similar in size. This could be the issue with yours, or you somehow could have ended up with 2 females. Either way id try to get a noticeably smaller clown next time and it should fall right into place as the male