Found in nearly all Minnesota lakes and streams except for the lower reaches of the North Shore creeks and the well-drained watersheds of the southeast. Prefers shallow, weedy, clear waters in lakes and marshes, but also inhabits slow streams. Small Northerns remain in shallow weedy waters through much of the year. They ambush prey from weedy cover, seizing fish with needlelike teeth. Concentrating their efforts on larger forage, they often swallow fish a third their own length.
Adults feed largely on other fish as well as frogs, crayfish, mice, muskrats, and ducklings.
Though eating sunfish and bass, they prefer more cylindrical fish. Fry feed on plankton and then invertebrates but soon switch to a diet of fish. Large Northerns become lethargic in warm water, eating little and sometimes losing weight. Because of their size and stealth, their only important predator is people. In the 17th century, Izaak Walton gave a recipe for roast stuffed pike that called for sweet marjoram, pickled oysters, mace, claret wine, and anchovies.