The name "bluegill" is derived from the fish's distinctive coloration, which is due to the presence of a pigment called cyanin in the skin cells. This pigment gives the bluegill its characteristic bluish-green color, which is most noticeable on the sides of its head, body, and gill covers. The bluegill's scientific name, Lepomis macrochirus, also alludes to its physical characteristics. The genus name Lepomis, derived from Greek roots meaning "scaly gill cover," refers to the scaly flap that covers the gills of this species. The species name macrochirus, meaning "large hand," refers to the bluegill's relatively large pectoral fins, which are used for swimming and balance.
The bluegill's coloration can vary somewhat depending on its environment and diet, but the bluish-green color is generally consistent across the species. The fish's color can also be affected by its emotional state, with males often exhibiting brighter coloration during breeding season to attract females.
Bluegills are typically found in shallow waters with clear vegetation and abundant cover. They are omnivores and feed on a variety of aquatic insects, small fish, and plant material. Bluegills are also known for their aggressive behavior and are often caught using live bait, such as worms or small minnows.