Like a female with the triangle fin. If they are going to "turn into" (for lack of better phrasing ) a male, then that triangle fin will slowly become a gonopodium.
It's neat to watch. You can actually see the fin changing day by day.
Grrr at buying females who turn into males. Happened to me, stupid "unsexed fish". Full grown... so I thought. Anyways, that was sorta on topic, sorry, I'm just a little bitter cuz I have two males now.