Whats Wrong With This Regal Tang?

[catxx]

just curious what's wrong with this guy, any ideas?

http/www.theaquariumwiki.com/Image:RegalTang-4454.jpg

 

[WILDER]

Can you say what you think is wrong as I cant make out what we are looking for.

 

[Colin_T]

The fish is a blue tang and should be blue all over with some black marking and a bit of yellow on it. The brown patching on the head is the problem and looks like a really bad case of head and lateral line disease (also called hole in the head disease). If it isn't HITH then it would be a really bad bacterial infection.

It would depend on how long the fish has had the problem for. If it only appeared in the last few weeks then it is probably bacterial. If the problem has been getting worse over the last few months then it is probably HITH.