So I think one of the fish in my tank has Cotton Wool Diease (Cotton Fin Fungus). I recently got 5 guppies from a LFS that has a great reputation. I noticed 2days ago (3days after purchase) one had white puffy fungus growing on its tail fin. The next day that portion of its tail was missing, but other than that he looks fine and he still eats & swims around without issue. None of the others have shown signs of the fungus. I did a partial water change & added aquarium salt (a suggestion I found online). I am worried that the other guppies might start showing signs; also I have the guppies to help with cycling the water to turn the tank (15gal) into a shrimp tank. Should I be worried about this sticking around & making my shrimp sick when I switch the tank over? Will the fungus come back even though my fish is doing ok 2days after?