Hello all. Recently I switched to a sand substrate, and five days later I've noticed a white growth coming from one of my cory's dorsal fin. It looks like cotton, which leads me to the conclusion that he has some sort of fungal disease. He probably got injured in the net when I took all the fish out (cories are fast when they want to be ). I'm thinking a salt bath would do the trick. I think I've caught it early. How much aquarium salt and water should be used in the bath? Is 20 minutes a good amount of time? What do I do if he passes out? Advice is welcome.