I had a beta a year ago in a tank with three other fish (platys). Turns out one platy was sick and after 2 days away I came home to three dead fish. My beta looked like it was ripped to shreds so I assumed it was fin rot. I cleaned the tank out extensively (it was a baby bio orb) and left it unused for a 11 months.
In April or March of this year I got a new beta. When I put him in the tank I noticed a day or two later his fins were starting to develop fin rot (small whole, few frays in fins) I immediately took him out and put him in a 1 gallon bowl. (I know a bowl is not ideal but I needed him out of that tank). He recovered quite nicely until a few days ago.
He now has fin rot again. I sterilized the bowl (no soaps just heat) and changed the water and he now has some clear "stuff" on his fins which I believe is re-growth. Since his tail was pretty far gone I decided to give him one does of bettafix in case his fin rot was severe. I put the bettafix in about 30 mins ago, but due to all of the horror stories I read about it (even though I read a ton of great thighs too) I'm now so scared. He is swimming around fine, has come up to the surface a few times but he isn't staying at the surface by any means. Is it possible he is gasping for air or am I just being paranoid? Any help would be greatly appreciated, I do not want this fish to go the way of the last.
Also...is it possible that the tank could have given it to him and will I ever be able to use it again? I would love for him to have more space but not at the risk of his health.
He is also a little jumpy lately...he just darted away as I tried to take a photo and he moves away when he sees my hands...
Sorry for the millions of questions