I had one that did the same thing a couple years back. I brought it back by feeding it formula one frozen cubes. About a half cube a day if I remember correctly. Maybe I just got lucky, or maybe it had a bunch more vitamins than just silversides. Since coming back though, I feed it silversides regularly and have had no more bleaching. It will take time. but just stick with it - took me about 6 weeks to fully come back.