We have caught a few sunfish that were decent sized but had a lot bigger mouth than a bluegill and little more greenish. I new that all the sunfish in the lake were legal with no size or number limit so we kept a two. I looked them up and they are the Green Sunfish.
Native to the Great Lakes, Hudson Bay and the Mississippi River basin. Introduced into Arizona in 1926. Large mouth with blue-green striations on the cheeks. Opercle flap is black with reddish or orange border. Bodies olive-green in color, dark vertical bars are faintly seen on sides. Pectoral fin short and rounded. Caudal fin and lower fin margins are white or yellowish with dusky spots at rear of dorsal and anal fins. Length: 3 to 12 inches. Weight: 3 ounces to 1 pound 8 ounces. May live to nine years.
I would love to find one of these that is 12" long. That would be a fun fight. Most sunfish put up more fight than a trout ever thought of. You even get to the point that you think that you have a medium sized bluegill on when it turns out to be a 13" trout.