I have two cory catfish with little white protrusions on them. I lost a Black phantom tetra from the same thing. I tried Ick Away, thinking that perhaps external parasites, and it seemed to clear up, then reoccurred. I tried Melafix, and that didn't seem to do anything. The white things almost look stringy, and seem longer at times. The corys are rubbing their sides on the gravel and the deco, like it itches, and they wont rest on the bottom of the tank. They hover about a inch from the substrate. Any ideas on what they have and how to treat it would be great. I don't want to lose them or any more fish.