HELP !! Fin Disease

Please help I bought two discus from a hobbyist saying that they were a proven pair ,but after bringing it home I realized that one of the discus had almost 1 inch of the fins missing its seems like as if some other fish has had a bite at it and the second one has a whole in the fin . after checking on google I came to know that it can be fin Disease , although they look quite healthy . swim ok eating i am not sure as they are just two days in my sixty gallon tank Please help me as I do not want to kill these fish.