What ever you do don’t place the fish in your display tank.. If the fish starts growing its fins back and starts making a recovery, I would make sure to put it through a few rounds medications. That fish looks to have a severe bacterial infection, and not to mention from the quality of that water it’s probably loaded with internal parasites as well. Keep the water good and clean and hit it with a double dose of stress coat to help. I wouldn’t hit him with salt until he’s more stable. Melafix would be my second round of treatment followed by prazi and some medicated food.
