Treating Popeye

[weezawoo]

In my OHs mums tank some fish appear to have pop eye. What is the best thing to use to help them? A QT tank isnt possible sadly.

 

[Baccus]

Can only suggest antibioticss and water changes, from what I've read about it there are two possible causes one (the more common is treatable) while the other is usually deadly,