The Mighty Green Sunfish

Happy Fish Friday, everyone!

This week I wanted to showcase a more common but still beautiful fish. Now, everyone that fishes or works with fishes have most likely come across this species at least once, if not thousands of times. I present to you the Green Sunfish (Lepomis cyanellus). Their defining characteristics are the following: elongated body, laterally compressed and heavy, large head and mouth, with a smooth tongue (lacks tooth patch), and 3-5 wavy blue lines on their face. They are often olive-green on their backs and yellowish-white on their stomachs. They have lines of iridescent blue-green spots that form rows and 7-8 dusky vertical bands along their sides. Their fins are outlined in white, yellow, or orange, and a black spot is found at the rear of their dorsal, sometimes in the anal fin. These fish are often confused with Warmouth and Rockbass, even Bluegill as juveniles.

A male Green Sunfish in breeding colors from the Scioto River, OH. Credit: Paul DeRolf

Green Sunfish reside in just about any freshwater habitat you can imagine. As a stream species, they are found most often in pools of small creeks using logs, rocks, and root wads as cover. In larger rivers and lakes, they can be found near shore, hiding in aquatic vegetation and woody debris. They are the most tolerant of the sunfishes, even most fishes, and are unfazed by turbidity, poor water quality, even extreme temperatures, and dissolved oxygen levels.

A Green Sunfish from the Cuyahoga River, OH. Credit: Paul DeRolf

The Green Sunfish has a big appetite and will utilize various food items. As juveniles, the most common prey will be aquatic insects and crustaceans. As adults, they will eat anything from aquatic insects to small fish species, even mice that fall into the water. They will swim around through the vegetation picking up whatever looks good at the moment.

A Green Sunfish x Longear Sunfish hybrid from southwest Ohio. Credit: Paul DeRolf

For the spawning season, males intensify in color, their fin outlines thicken, and the facial streaks brighten. They form nesting colonies near shore, building circular depressions in sand or gravel substrates. Nests are built any time from May to August. Males will attract a mate with their colors and then guide the female into the nest to lay her eggs. The male will guard any eggs until they hatch then attempt to attract another female for another round of mating. Hybrids between Green Sunfish and other sunfish species are common, mainly because female Green Sunfish will lay eggs in other nearby nests. The most common hybrid is Green Sunfish by Bluegill, which is commercially important. This hybrid is often sold for stocking ponds because they are sterile and show excellent hybrid vigor (traits from both parents are enhanced in the hybrid offspring).

A Green Sunfish x Pumpkinseed Sunfish hybrid from Mill Creek, OH. Credit: Paul DeRolf

Green Sunfish have a wide native range that spans the Great Lakes, Hudson Bay, Mississippi River basins, along with the Gulf Slope drainages from Mobile Bay to the Rio Grande and parts of Northern Mexico. They have been introduced to all Lower 48 States and portions of Hawaii. The main reason for these introductions was that they were mistaken for Bluegill. The second reason is they were used as baitfish outside of their native range. Once established, they took over and began to expand throughout watersheds. The introduction of Green Sunfish has had negative impacts on the native fish assemblages. Some examples would be competing with Colorado Pikeminnow (endangered), preying on Gila Chub (endangered), and altering population structures in piedmont streams of North Carolina. *Even though they are common please do not continue to transplant these or any other species outside their range.*

Range map of Green Sunfish. Native ranges in orange, introduced areas in red. Credit to the USGS for the map

There is no wrong way to observe Green Sunfish. The best and easiest way is to fish for them. You can also snorkel in the shallows around vegetation or other structure to get face-to-face with them. Green Sunfish can also make for a great aquarium fish. They have big personalities and can be aggressive towards tankmates, so you’ll want to keep them alone or with other species they won’t bully. No matter how you decide to see them, remember to make sure that you enjoy, protect, and enhance our freshwater ecosystems!