I have 2 gars which seem to have some sort of disease and don't know what to do? I want to try and add some aquarium salt to the tank to see if anything happens. Can the salt harm any of the fish!? It would be the 300g fish in my sig who would have to cope with the salt. How much should I use? Mix it with water before it goes in the tank right? or do I just ad to the sump? Do you guys think this will work? The gars' disease has pics posted in ancient fish-gars