Fish Burns

[chibi]

My synodontis has a big white spot on his side. It's not ich. It's about a half an inch in diameter. He is constantly behind my heater so I'm wondering: What does a burn on a fish look like?

 

[bigstevo]

Is it possible of a picture?

 

[WILDER]

A pic would be good.
The spot does it have a tinging of red around the outside of it, or a red centre.