The bluegill has 39 to 44 lateral line scales. Its dorsal fin contains nine to 11 spines and 10 to 12 soft rays, its anal fin three spines and 10 to 12 rays. The pectoral fin is long and pointed, extending past the eye when bent forward. The mouth is small; the upper jaw does not extend to the front of the eye. Always black, the flexible ear flap is small in juveniles, longer in adults. Juveniles and nonbreeding adults are light olive to gray on the back and sides with several evenly spaced, darker vertical bands. The venter varies from pale yellow to white. All but small individuals have a distinct black spot toward the rear of the soft dorsal fin. Breeding males darken, with the back and sides becoming purple. Adult size: 6 to 10 inches.