Lepomis macrochirus, commonly known as the bluegill, is native to North America, specifically widespread across the eastern and central regions of the United States. It is also found in parts of northern Mexico and southern Canada. Despite its native range, the bluegill has been widely introduced to other regions for sport fishing.

The bluegill typically inhabits freshwater environments with warm, slow-moving waters. They are often found in ponds, lakes, rivers, and reservoirs. The species prefers habitats where aquatic vegetation is abundant, which provides cover and breeding grounds.

Bluegills are primarily found in the littoral zone where they have access to ample food sources and cover. They thrive in water temperatures ranging from 60 to 80 degrees Fahrenheit (16 to 27 degrees Celsius). In their ecological niche, bluegills serve as both predators and prey, feeding on small invertebrates, insects, and small fish while being a primary food source for larger predatory fish.