Green Sunfish

Characteristics

A thick-bodied sunfish with a large mouth for sunfishes; the upper jaw extends to about the middle of the eye when the mouth is closed. The spiny dorsal fin has 10 spines and is broadly connected to the soft dorsal fin. The pectoral fins are short and rounded, and the ear flap is never elongated. The back and sides are bluish-green with emerald and yellow reflections, while the belly is white or light yellow. Sometimes there are several black vertical bars on the sides. The sides of the head are mottled with emerald and yellow streaks, and the black ear flap has a whitish or yellowish margin. Green Sunfish usually have whitish or yellow-orange leading edges on their dorsal, anal and caudal fins.

Distribution

Every watershed in the state; found in streams of all sizes, but reaches its greatest abundance in natural lakes, man-made lakes and farm ponds. Lives in the full length of the Mississippi River, and is prevalent in the prime habitat created by the rip-rap armoring placed along the banks of the Missouri River.

Foods

Zooplankton make up a large part of the diet of small fingerling Green Sunfish, but later in the first year they switch to aquatic insects. As adults they continue to rely on aquatic insects, but also eat small fish, minnows and small crayfish. Since this species has a large mouth, it eats larger food items than most sunfishes.

State Record

2 pound 1 ounce, 12 1/2 inches, farm pond, July 2000, Ralph Mayer, Knoxville, Iowa

Expert Tip

Green Sunfish are not selective feeders, they can be caught easily on most types of live bait, as long as the hook is small enough to fit into their mouth.

Details

Green Sunfish are one of the most widely distributed fish in Iowa, and is the most wide-ranging sunfish species. It can be found in a variety of habitats, from small muddy creeks and weedy backwaters with temporary flow to overflow ponds, shallow lakes, impoundments and occasionally, the margins of large rivers of low gradient. It is commonly found near shore and around cover, like stems of vegetation, woody debris, or rocks, and has no specific substrate preference. Its high tolerance for extremes in turbidity, siltation, low oxygen, temperature and flow allow it to live in, and reach greatest abundance, in areas that do not support other sunfishes. In Iowa, the Green Sunfish is well adapted to survive in small streams with intermittent flow that become stagnant pools late summer and fall. A pioneering species, it is often the first fish to find its way to newly created farm ponds, and first to repopulate streams after droughts.  

Green Sunfish share similar reproductive habits with Bluegill, nesting in colonies in shallow water near the shore -- often times in the same spot. Nest preparation starts when the water temperature reaches 70 degrees, usually in mid-May and June, but more often in June. The nests are found in about a foot or less water over gravel or sand, but if these sites are unavailable, the male will fan nests in water-soaked tree leaves or twigs and muck. Small territories are established and vigorously protected by the male, but if nesting sites are limited, as many as 25 nests may be built in 50 square feet. Once the eggs are deposited, the fighting among males stops, except when one fish invades another`s territory. Males stay with the eggs for 6 or 7 days, at which time the fry become free-swimming. There is considerable cross mating of Green Sunfish and Bluegill.

Green Sunfish reach up to 7-inches long by the fourth year. Most fish become sexually mature at two years. Green Sunfish rarely exceed 6-or 7-inches long.

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.

Sources:

Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.

Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames

Illustration by Maynard Reece, from Iowa Fish and Fishing.