Sick platy

[angel555]

I have a very sick platy who has lost loads of weight and hangs near the surface of the tank. She also keeps losing her balance and hangs upside down, although she does correct herself. She is not eating much and her breathing is rapid. I have treated for internal bacteria and nothing has changed. She has been like this for a week. I am pretty sure she is going to die, but I am concerned about my other fish as I have another 12 plattys, gouramis, kribs and fry and neons and I don't want any of them to catch what she has. What should I do? (No other fish are sick or have died)

 

[WILDER]

Can you issolate the fish, it not sounding good i'm afraid,she's past helping now, you couldn't use a med as the swim bladder has progressed, and she is heavy breathing so the med won't help, as it takes 02 out of the water, sorry.