Salt is the only thing that I have used. Twice in the last 5 months it has popped up and it is the same gar every time. I have separated him to Qt tank and used salt as treatment with raised temps. and he heals only to go thru it again. My only option is to keep him out of the community tank. Filters are cleaned every couple of weeks or when needed. What would be the bigger problem? I will take him out again and treat both tanks and see if this helps.