I think my betta may have fin rot as his fins are looking pretty ripped around the edges. Im doing regular water changes and using aquarium salt first. I know I can get medication if this doesn’t work, I was thinking of moving him to a smaller hospital tank if he doesn’t improve. Do I need to set up a tank now and start cycling it which could take months? Or do I use water from my existing tank? How do hospital tanks work in emergencies?