Sick Platy

[CaspianRain]

One of my younger platys is sick. She can't swim and her fins are always moving, but she herself is in one place. She can't come up to get food either, obviously. Also, she is on her side right now, and manages hard to sit up whenever I enter the room.

The water is perfectly fine, all the other fish are perfectly fine. I don't know what is wrong with her.

Is this swim bladder or what? How can I save her?

 

[WILDER]

Can you post water stats please.
Size of tank.
How many fish and which type.

Does she look bloated.
Dosn't sound like the fish can maintain balance in the water, is this correct.