Bluegill

The bluegill is a deep-bodied freshwater sunfish native to lakes, ponds, and slow streams east of the Rocky Mountains, recognizable by its blue and purple face, a dark ear-shaped flap on each gill cover, olive side bars, and an orange to yellow belly. It typically grows to 10 to 30 centimeters, feeding on aquatic insect larvae, zooplankton, small fish, and vegetation. Introduced widely for sport fishing, it has become an invasive nuisance in parts of Asia and elsewhere outside its native range, even as it remains a popular panfish and the state fish of Illinois.