sexing clownfish

[corally]

My two false perc clowns look to be about the exact same size. How will one become the female, and when does that happen?

 

[thegrog]

They decide on their own. One will become dominant and turn female. They are born hemaphrodites (both sexes) and can change from male (default ---) to female....but not female to male.
In Ocellarius (aka False Percs) clowns, the female is not much bigger than the male until theya re fully mature (about 1-1/2 to 2 years). If you got a pair as juveniles, they will --- themselves eventually.