[6] The green sunfish is considered an invasive species by the states of Arizona, California, Florida, Georgia and New Jersey,[3] with unconfirmed presence in Vermont and New Hampshire, namely the Connecticut River and its tributaries.

[7] Their invasive potential is due in part to their penchant for chasing other sunfish away from mutually preferred habitat of submerged vegetation, a form of interference competition,[8][9] their relatively large mouth,[10] high fecundity and ability to tolerate sediment pollution.

[11] In the state of Florida, a permit is required in order to possess green sunfish as it is listed as a prohibited non-native species there.

The gill covers and sides of head have broken bright blue stripes, causing some to mistakenly confuse them with bluegill.

[17] The species prefers areas in sluggish backwaters, lakes, and ponds with gravel, sand, or bedrock bottoms.

Green sunfish tend to spend their time hiding around rocks, submerged logs, plants, and other things that provide cover.

Green sunfish begin spawning in the summer with the exact time varying with location and water temperature.

When they do spawn, the males create nests in shallow water by clearing depressions in the bottom,[18] often near a type of shelter such as rocks or submerged logs.

[25] The International Game Fish Association (IGFA) all-tackle world record for the species stands at 0.96 kg (2 lb 2 oz), caught from Stockton Lake, Missouri in 1971.

The green sunfish accepts a variety of foods, including flakes, pellets, krill, brine shrimp, bloodworms, and live prey.