Grant, what type of tank do you have fish only, reef, inverts...??? If fish only there are tons of copper based treatments that will work wonders, but if you have any inverts or corals you may need to isolate him and treat in a separate tank. If it is ich or velvet try using a product called coppersafe from Mardel Laboratories (most fish stores have it) a long time ago I had an ich outbreak and it worked wonders.