The Filet-O-Fish is a brand name of fish sandwich sold by the international fast food restaurant chain McDonald's. It was created in 1962 by Lou Groen, a McDonald's franchise owner in a predominantly Catholic neighborhood of Monfort Heights in Cincinnati, Ohio, in response to declining hamburger sales on Fridays due to the practice of abstaining from meat on that day. While the fish composition of the sandwich has changed throughout the years to cater to taste preferences and address supply limitations, the framework of its ingredients has remained constant; a fried breaded fish fillet, a steamed bun, tartar sauce, and pasteurized American cheese.