The Grass Pickerel is largely restricted to the west of the Appalachian Mountains, in the Great Lakes and the Mississippi River basins. It extends from southwestern Quebec southwest to Texas and, in the north, west to Minnesota. In Canada, its range is disjunct and is represented by several populations in southwestern Quebec and southern Ontario. It is known in the lower Ottawa and St. Lawrence rivers, as well as in shallow bays and tributaries of eastern and southwestern Lake Ontario, and along the north shore of Lake Erie. Populations occur in Lake St. Clair and some of its tributaries. It is also found in several tributaries in the Lake Huron watershed. The habitat of the Grass Pickerel is characterized by warm, slow-moving streams, ponds and shallow bays of larger lakes, with clear to tea-coloured water, and abundant aquatic vegetation. Bottom substrate is usually mud with exceptions of rock and gravel.

The Grass Pickerel has a large mouth, many teeth, forked tail, and posterior dorsal and anal fins. Its long, relatively shallow body is cylindrical to subcylindrical in shape. Grass Pickerel vary in colour but are usually green to brown with 12 to 24 irregular, vertical, narrow, dark bars and a mid-dorsal brown stripe. They also have a dark bar is below the eye. They are usually less than 300 mm in length with a maximum total length of 381 mm and weight of 397 grams. Adults reach sexual maturity by two years of age. The lifespan of the Grass Pickerel is seven years or less.