Wow, that is cool. I don’t know if sunfish and crappie can crossbreed (never heard that they could) but if they do, you may have found one of the offspring.
Did you eat it? Did it have eggs? Looks really fat. Since I don’t think they can crossbreed, I’d guess it is either a fat female bluegill in spawning dress or a hybrid of a bluegill and another sunfish. You could send the pict into the DNR for their explanation. If you do, let us know what they say.
Very cool, thanks for sharing.