Could simpley be a mild bacterial problem, if so meds won't typically be needed. In most cases several large water changes with well aged/aerated SW
will clear it up. The water changes reduce the DOC
in the water which will help starve the bacteria. Also be sure to bolster the fish diet with vitamin ([acronym="Highly Unsaturated Fatty Acid"]HUFA
[/acronym]) fortified foods.
If it gets worse or doesn't abate after a few weeks, it could be a true fungal infection (quite rare) and may need to be QT
'd and treated. Start with the above first and move on from there. Try a google image search for Lymphocystis and fugal infections and see if either look similar to your fish.