Bio Facts: Bluegill
A wide area of North America, from Québec to northern Mexico, and has been widely transplanted to stock game fish for anglers
Freshwater lakes, ponds, reservoirs and sluggish streams and slow-moving, rocky streams
Adult length: 16 in (40 cm); bluegills may be distinguished from other sunfish by the dark spot at the base of the dorsal fin, vertical bars on their sides, and a relatively small mouth. The spiny dorsal fin usually has 10 spines (but may have as many as 11 or as few as 9), and is broadly connected to the soft dorsal. The anal fin has three spines. The back and upper sides are usually dark olive green blending to lavender, brown, copper, or orange on the sides, and reddish-orange or yellow on the belly. Colors are more intense in breeding males, and vertical bars may take on a reddish hue. One of the most distinguishing characteristics is the dark blue or black “ear” on an extension of the gill cover called the opercular flap.
In the wild: 5 – 6 years; in captivity: 8 – 11 years
1 - 2 years
In the wild, they eat aquatic invertebrates; in the Zoo, they are fed a scientifically developed, commercially available fish food and a variety of worms.
IUCN – Not Listed
Bluegills are most active at dawn. During the day they stay hidden under cover and move to shallow water to spend the night. They 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.
The bluegill is a schooling fish with schools of 20–30 individuals. These fish spawn in June in nests in the shallows. During this period males assume a very bold coloration, as they are guarding their nests. An interesting piece of their biology is that some males assume the coloration of the female fish so that the nest guarding males won’t show aggression towards them. Then these “sneaker” males enter nests and spawn.
Males make nests in colonies with 20 to 50 other males in shallow water less than 3.3 ft (1 m) deep. The nests are circular shallow depressions, about 7. 9 – 11.8 in (20 – 30 cm) in diameter, in sand or fine gravel from which the male has fanned all debris.
Once his nest is made, a male waits in it and grunts to attract females. When a female enters, they swim in circles. Eventually they stop and touch bellies, the male in an upright posture and the female leaning at an angle. She releases eggs and he sperm and then they start the process again by swimming in circles.
A female deposits her eggs into several nests, and a male’s nest may be used by several females. Males guard nests both before and after females lay eggs. Paternal care involves fanning the eggs and chasing away predators.
Young fish feed on plankton, but as they grow the diet shifts to aquatic insects and their larvae. Up to 50% of their diet may consist of midge larvae. Sunfish are particularly prone to “stunting.” Lakes that have good spawning habitat but not much food can produce swarms of small adult sunnies that never grow larger than four or five inches.
Lepomis, the generic name, is Greek and means “scaled gill cover”. The species name, macrochirus, is also Greek and means “large hand” which may refer to the body shape or its size. Bluegills are often called by other common names: bream, brim, perch, sunfish, and sunperch. Because of their size and the method of cooking them, bluegills are often called panfish.
The bluegill is the state fish of Illinois.
Adult channel catfish, largemouth bass, northern pike, muskellunge, and turtles prey upon bluegill.
Although less than one percent of licensed Texas anglers say they “prefer” to catch sunfish, bluegill and other sunfish are nevertheless a vital part of many freshwater fisheries nationwide, including Texas. Many pre-license age anglers begin their fishing careers by bank fishing for bluegills and other sunfish. Bluegills provide plenty of fight, pound for pound. In Texas, bluegills approaching two pounds have been landed in public waters, and fish over three pounds are known from private tanks. The largest bluegill on record was 4 pounds 12 ounces, landed in 1950 from Ketona Lake, Alabama.
From Colorado, “Back in the spring just about the time our cottonwoods leaf out and the lilacs reach full bloom, you know the bluegills are moving from their deep-water winter sanctuaries to the sun-drenched shallows of lakes and ponds in preparation for their annual spawning ritual. This knowledge is based more on folklore and tradition than actual science, but it is surprisingly accurate for predicting bluegill activity.”
In some locations where it has been transplanted, it is considered a pest: trade in the species is prohibited in Germany and Japan. In the case of Japan, bluegills were presented to the Crown Prince Akihito in 1960 as a gift by Richard J. Daley, mayor of Chicago. The prince, in turn, donated the fish to fishery research agencies in Japan from which they escaped, becoming an invasive species which has wreaked havoc with native species, specifically in Lake Biwa in Shiga Prefecture. The emperor has since apologized.
Jacksonville Zoo History:
Our earliest record for a bluegill in our animal collection is 1989. We have held the species 1989 to 1991, 1993, and 2009 to present day.