I noticed that the eyes of one of my Discus look a little strange compared to the other Discus, and its lost its colour, look at it on the pics and compare it to my signature pic (top left Discus). Also its cr@p is white.
awww the poor thing.. I dunno. I seen a oscar with that in pets@home and it said on the tank they were keeping it for a customer while it recovered from a illness but I really dont know. good luck in finding out.