I have a clownfish that has what I believe is cottonmouth. He has a large white cottony growth around his mouth and then two white growths on the front lower edge of his pelvic fins. He has been treated the last 3 days in a separate 10gal tank with erythromycin (E.M. tablets, Aquarium Pharmaceuticals), one tablet/day, but it doesn't look like anything is happening. I had previously tried several formalin dips, but that also had no effect. Any suggestions on what I ought to try next?