you have two clowns, are they the same species? do you notice the other one picking on this one that's fading? i have 2 ocellaris clowns and the smaller one lost some color since i added him, but it's starting to return now. it was more than likely all the stress from being picked on all the time. he still gets picked on, but i don't think it's quite as bad as it was, and he is starting to get the color back in his face. he's a black ocellaris so just his face is orange, and the orange faded.
HTH :happyfish