I have two largemouth bass in a 75 gallon aquarium. They are not wild caught. I got them from a fish farm near my house and have had them for about 5 months. They are about six inches long and i just realized that one of them has what looks like white mold or something growing on his fins. He acts healthy and the other fish has nothing like this on him..Should I get rid of the one before the other one gets sick or is there anything i can do.