I have a red wag platy that seems to have algae growing on it. It's just a green slime that stretches from its gills to its dorsal fin. I had it in a healthy 5 gallon tank. It is pretty new but it has been cycled for 2 weeks now. I just moved the fish into a one gallon quarantine tank for now just in case it is a spreadable disease. I did put one teaspoon of kosher salt in the tank but that hasn't done any good. What can I do?