I've never caught one with such a pronounced humped head as this bluegill. His eye was huge as well. From what I have read it's an old male bluegill aka "stump knocker". He had a nasty scar on his side as well. Probably should have removed him but didn't.

Fun catching, regardless...

http://farm4.static.flickr.com/3305/...0cc0821d_b.jpg