Fish lice. This is one I haven't had to deal with before... I'm not sure the old salt bath will have any effect as lice aren't a fungus, bacteria or protozoan (they are a argulidae, a type of parasitic crustacean)... but I really don't know much on this one.
My buddy Matt did some quick research and came up with Dimilin as a treatment method for fish lice. My googling came up with emamectin. Not sure how these go with the nitrifying bacteria.
I'm wondering if anyone here has ever had any experience with this fish lice business. Dimilin sounds ok according to the toxicology paper I've linked, but hmmmmm I'd sure like to hear about any experiences people have had.
Fish Lice: http://en.wikipedia.org/wiki/Argulidae