Fish Identification Photos: Bluegill, Lepomis macrochirus: The Bluegill has been widely transplanted and is now the most common recreational freshwater fish in North America. It is a schooling fish found in schools of 20 to 30 individuals. The Bluegill is caught with live bait, flies, white bread, corn kernels, hot dogs, raw chicken or lures at dawn and dusk. It is found in waters with underwater vegetation.

The Bluegill has a long spawning season that begins when water temperatures reach 70 degrees, peaking in May or June, and continuing until water temperatures cool in the fall. Nests are created in shallow water, one to two feet in depth, over gravel substrate. Fifty or more nests may be crowded into a small area, thus creating a spawning bed. Very territorial males guard the nests until the eggs hatch and the fry leave. Young fish feed on plankton, but as they grow the diet shifts to aquatic insects and insect larvae. With high reproductive rates, low predation and low fishing pressure the Bluegill can very quickly become a major invasive pest destroying native populations; it has been banned from commercial trade in Germany and Japan. The Bluegill is preyed upon by catfish and largemouth bass.

The Bluegill is currently used by the cities of New York, San Francisco and Washington to monitor freshwater water quality supplies for toxicants such as cyanide, fuel spills, heavy metals, mercury, pesticides, and phosphates. The Bluegill coughs by flexing its gills to expel unwelcomed materials from its breathing passages. The frequency of these coughs is monitored by sensitive listening devices giving an indication of current water quality.

The Bluegill is a member of the Centrarchidae or Sunfish Family. They are fairly easy to recognize by the blue or black “ear” which is an extension of the gill cover, vertical bars on the sides, and a relatively small mouth. Breeding males are intensely colored with the vertical bars taking on a reddish hue. They are named, however, for the bright blue edging on the gill rakers. They are found throughout North America ranging from Québec to northern Mexico and are the state fish of Illinois. Pound for pound they provide an excellent fight, reaching a maximum length of 17 inches; the largest Bluegill on record is 4 pounds 12 ounces caught in 1950 from a lake in Alabama. They are considered to be an excellent species for teaching angling to children and an excellent food fish.

Bluegill, Lepomis macrochirus: Caught by Eduardo Correa with a fly rod out of an irrigation pond at Los Cabos, Baja California Sur, Mexico, August 2008. Size 18 cm. Description and photo courtesy of John Snow.