The Bluegill is a species of freshwater fish. It is a member of the sunfish family Centrarchidae of the order Perciformes. Lepomis, in Greek, means "scaled gill cover" and macrochirus means large hand, which may be a reference to its body shape. A defining characteristic of the Bluegill is the bright blue edging visible on its gill rakers. Bluegill live in the shallow waters of many lakes and ponds, along with slow-moving areas of streams and small rivers. They prefer water with many aquatic plants, and hide within fallen logs or water weeds. Young Bluegills' diet consists of rotifers and water fleas. The adult diet consists of aquatic insect larvae (mayflies, caddisflies, dragonflies), but can also include crayfish, leeches, snails, and other small fish. Bluegills have the ability to travel and change directions at high speeds by means of synchronized fin movements. They use notched caudal fins, soft dorsal fins, body undulations, and pectoral fins to move forward. Having a notched caudal fin allows them to accelerate quickly.
The Bluegill is noted for the darkened spot that it has on the posterior edge of the gills and base of the 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 are not always 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 12 anal fin rays, six to 13 dorsal fin spines, 11 to 12 dorsal rays, and 12 to 13 pectoral rays. They are characterized by their deep, flattened, laterally compressed bodies. They have a terminal mouth, ctenoid scales, and a lateral line that is arched upward anteriorly. The Bluegill typically ranges in size from four to 12 inches(10-30cm), and reaches a maximum size just over 16 inches(40cm). The largest Bluegill ever caught was four pounds, 12 ounces(2kg) in 1950. The Bluegill is most commonly related to the Orangespotted Sunfish and the Redear Sunfish, but different in a distinct spot at or near the base of the soft dorsal fin.
Bluegills are popular panfish, caught with live bait such as worms or crickets, grasshoppers, flies, pieces of corn, small crankbaits, spinners, American cheese pushed around a hook, maggots, small frogs, bread, or even a bare hook. They mostly bite on vibrant colors like orange, yellow, green, or red, chiefly at dawn and dusk. They are noted for seeking out underwater vegetation for cover; their natural diet consists largely of small invertebrates and very small fish. The Bluegill itself is also occasionally used as bait for larger game fish species, such as Blue Catfish, Flathead Catfish and Largemouth Bass.
Fishermen are sometimes able to use polarized sunglasses to see through water and find Bluegills' spawning beds. Bluegill have a rather bold character; many have no fear of humans, eating food dropped into the water, and a population in Canada's Lake Scugog will even allow themselves to be stroked by human observers.
Although the majority of Bluegills are caught on live bait—particularly worms, leeches, grubs and crickets—they can also be taken on tiny artificials such as jigs and spinnerbaits. They will rise to small poppers, sponge bugs and dry flies. They will also take wet flies, nymphs, and small streamers.
The Bluegill occurs naturally in the United States east of the Rocky Mountains from coastal Virginia to Florida, west to Texas and northern Mexico, and north to western Minnesota and western New York. Today they have been transported almost everywhere else in North America, and have also been introduced into Europe, South Africa, Zimbabwe, Asia, South America, and Oceania. Bluegill have also been found in the Chesapeake Bay, indicating they can tolerate up to 1.8% salinity.
In some locations where they have been transplanted, they are considered pests: trade in the species is prohibited in Germany and Japan. In the case of Japan, Bluegill were presented to the then-crown prince, Akihito in 1960 as a gift by Richard J. Daley, mayor of Chicago.