Hi RobIt sounds like a natural mucus that I've seen on some Sterbai cory before, is it like a grey thin cloudy mucus?I would just keep an eye on it without using medications.Most of us are now residing at http://www.aquariumforums.co.uk including myself.The tropicalfishforums has basically died a death due to the lack of support from the current owners.I and a few others tried hard to keep it going but have now given up the ghost.Come and join us.Please say Stephen referred you. (just type Stephen in the referrer box on registration).All the bestStephen