Help with my severum...pics attached

[razmataz1971]

I've had this guy since he was the size of a quarter now he's about 10-12 inches in diameter. Going on 4 years old now. He's developed something on the top of his head that I have no clue on what it is. Kind of almost looks like a fungus, but with 4 white dots similiar to ich. He eats well and doesn't appear to be distressed. I tried to get decent enough photos for you guys so you help diagnose what this is. What do you all think?

 

[OniTweak]

Looks like HITH(Hole in the Head) Disease to me.

Here is a resource for you.
Hole in the Head disease (HITH) (FISH DISEASES ARTICLES)

 

[Zagz]

I agree it does look like HITH disease. Usually caused by water quality issues and/or stress. First thing to do is a large water change and keep doing them to keep the water pristine.