Fungus is usually a secondary infection brought about by a weakened immune system due to other diseases or bad water quality. Bad water quality is most often the cause, diseases second.
IMO the best treatment for fungus is to start with fresh water and lots of it. Could you post your ammonia, nitrite, nitrate and pH readings, please?
Do 50% water changes every day and see if that helps. If it does not, then there may be another cause for the fungus.
Salt really isn't necessary for treating fungus.
Roan