That's Head and Lateral Line Erosion, or HLLE. It sometimes affects the fish's dorsal fin in severe cases, but you usually see that on tangs, not clownfish.
I'm not sure what you're seeing around the eyes - the cheek spine perhaps?
You can run a search for treatments of HLLE, but beware that there is a lot of hokum out there. Avoid "cures" that discuss grounding probes, HUFA additives or garlic. The known causes are carbon dust, poor water quality and possibly lack of vitamin C (although adding vitamin C rarely cures the problem).
In some chronic cases, the scars are too deep and won't heal. In most cases where the problem goes away completely, the fish was subsequently moved to a new aquarium at some point. Since you brought the old tank along with this clown, that "known cure" isn't an option.
The good news is that this is usually a chronic issue and not normally fatal. It is also not contagious (except that the tank conditions that prompted it will affect other fish as well).
JHemdal
