Any of several large North or Central American fishes of the genus Lepisosteus .
They are related to the bowfin and date back to the Eocene Epoch . Gars are confined chiefly to fresh water, though some species enter brackish or salt water. They frequently bask at the surface in sluggish waters and commonly breathe atmospheric air. Their jaws and face form a sharp-toothed beak, and their body is encased in an armour of diamond-shaped, thick scales. Their eggs are toxic to predators. They are highly voracious predators, with long rows of needlelike teeth. The alligator gar of the southern U.S. reaches a length of about 10 ft (3 m) and is one of the largest freshwater fishes.