The Filet-O-Fish introduced McDonald’s first fish sandwich in 1963.
Franchisee Lou Groen developed the sandwich for a Cincinnati restaurant in an area with many Catholic customers who traditionally avoided meat on Fridays. The original sandwich used a breaded fish fillet, tartar sauce, and cheese on a bun.
The item gave McDonald’s a way to attract customers during periods when hamburger sales could fall. It also broadened the brand’s menu beyond beef without abandoning the chain’s fast-service format. The sandwich became a recurring seasonal and permanent menu product in many markets.
The Filet-O-Fish is sometimes described as a national menu item from its first day. It began as a local franchisee innovation and was tested before wider adoption. The fish species and preparation have varied by country and period, so the product’s exact ingredients are not identical everywhere.