Very interesting article
http://www.outdoorhub.com/how-to/2014/11/24/recognize-9-common-game-fish-diseases/
(http://i57.tinypic.com/28bfvo7.jpg)
Those are some nasty looking diseases, and would definitely not eat any of the filets off one of those fish. Can't say I've ever noticed any of them in fish I caught, but have found some type of worm that is embedded in some sunny and crappie filets. White, and maybe an eighth of an inch long.
Its funny you say you that, I've found those in bluegills and sunfish up here too.
I have also seen the one they call Neascus (black spot disease)