someone please help.I currently have 4 discus and all of them seem to be suffering from some kind of excess mucus production on there skins along with fin rot.I have treaeted them over the past week with protozin which hasent helped at all other species in the tank are not affected atall at the moment my discus look like they have a silver outline allaround the edges of there bodies im on top of my water condition and for the life of me cant seem to cure this or work out what it is they have please help