Can Platies change gender?

[FrankSlapperinni]

A few months ago, I set up a 10 gallon aquarium in my dining room, and have meant to buy more residents, but I still only have two platies in there. anyways, when I bought them, I specifically singled out a male and a female, and both those, when they were in my tank for the first few months, Patrick and penny were all just fine, but about a month ago, Penny's Fan shaped anal fin suddenly folded up, not too unnatural, but now she/he keeps it folded up, and it looks more like a gonopodium, and now I'm almost sure it's a male.
Any idea of whats up?

 

[Angry_Platy]

You may have bought them when they were young and he/she hadn't quite developed the characteristic male anal fin. Its a pain though if you wanted to breed them.

They don't change sex spontaneously....the only way sex can be controleld is through the pH of the tankwater the fry are born into. Depending on the pH of the water you will have more males or females (I'm not sure of the pH or anything).

 

[Sasha]

It is quite normal for females to turn into males. Actually, it's an undevolped male and that's why they change gender later on.

I had a swordtail that I was sure was a female and it developed into a male and starting growing a sword on it's tail. Now, one of my female guppies is changing into a male and my platy did too.