Without a picture it is hard to tell by I would guess that your goldfish has some tumors. Whether they are benign or not is hard to say without of course a biopsy. If your curious, you could take your fish to an aquatic vet but he has lived a long life already. It is also hard to say what the color loss is from. Color loss can be from stress, sickness, old age, diet or genetics. If the tumors don't seem to bother him, then I would just let him live out is life as comfortably as possible.