I have the kind that lazytaper mentioned, but I have seen juveniles that don't have the orange nose. I really don't know much about them, but I have never heard of them losing black. In addition to losing the orange noses, the bodies of black ocellaris will usually darken as they grow. So normally they will change from a brownish color, to more of a true black, which I have never heard of them losing.
Is there any way you could get a picture?