ID please

[Neebles]

Sorry for the lousy pic (if it even shows up)
Anyway this seems to have developed on my foxface overnight, he certainly didn't have it yesterday. It's a perfect black circle, I can see yellow in the middle... I do have a sharknose goby who like to clean the foxface, could it be a bite? The foxface is actively swimming, no scratching or anything like that. He is eating like a pig and has good color otherwise. Any idea what it could be?

[IMG=http://imagizer.imageshack.us/v2/150x100q90/673/prQqxc.jpg][/IMG]

 

[snorvich]

What is the history of this fish? When was the last wet item added to your tank?

 

[Neebles]

I've had him for about a year. Last wet item was a piece of coral, on rock, but was dipped first. That was probably a month ago.