Betta seems to have some fin rot going on. I'm really not entirely sure what all is going on with him, actually. Definitely some fraying on his tail but two days ago I found him lying sideways on the gravel in his tank. A couple days before that he was eating just fine so I took him out and put him in a cup. He didn't move much at all, just sunk in the water and when I got him in the net, he didn't move. I was pretty sure the next morning he'd be dead but I set him up in a little makeshift 5 gallon hospital tank. Full water change, some aquarium salt, and all that. The next morning he was swimming around the tank. 2 days later and he's eating well and is fairly active if not 100%. He's no longer having trouble staying upright. Anything else I should be doing? How long will it take to see some changes on his fins?