Platy With White Shimmer And Fins Not Spread

[Rawb0]

Hi All,
 
I have a tank with 6 platy, all are healthy except one that yesterday started to get a white shimmering look towards the back of the fish.  Today the white'ness has spread to almost the whole fish and her fins are close to her body and not spread.  Its hard to get a decent picture but the best I can do is attached:
 

 
I've just been out and when I returned, she was resting on the bottom in the corner but is now swimming around with the rest of the Platys.  The tank is 54l with 6 platys and it has a 20% water change at least twice a week.
 
The fish itself has only been in the tank a week.
 
Any suggestions ?  Should I move it to another tank and quarantine it or leave it alone ?
 
Edit: Probably irrelevant but she keeps swimming up to the top of the bubbles from the airstone and staying there for long periods.
 
Thanks for any advice,
Rob.

 

[Akasha72]

Hi Rob and welcome.
 
This sounds like some kind of fungus and so I would treat with with an anti-fungal medication. There are many on the market, Esha is a good brand as is Waterlife and TAP fish doctor
 
This could spread to your other fish and so I would treat the whole tank.
 
Hope that helps

 

[Rawb0]

Thanks for the advice.

I moved her to a separate tank and will try with some meds tmrw.

Thanks,
Rob.