Bluegill are characterized by their deep, flattened, laterally compressed bodies.
The bluegill is noted for the dark spot that it has on the posterior part of its dorsal fin. The sides of its head and chin are a dark shade of blue. It usually contains 5-9 vertical bars on the sides of its body, but these stripes aren't aways distinct. It has a yellowish breast and abdomen, with the breast of the breeding male being a bright orange. The bluegill has three anal spines, ten to twelve anal fin rays, six to thirteen dorsal fin spines, eleven to twelve dorsal rays, and twelve to thirteen pectoral rays.

