Lou Groen created the McDonald’s Filet-O-Fish, first sold in 1962 to attract Catholic customers on Fridays.
Groen operated a McDonald’s franchise in a heavily Catholic Cincinnati neighborhood. He noticed that Friday restrictions on eating meat reduced hamburger sales, creating a business problem for the restaurant. His solution was a fish sandwich that could be sold alongside McDonald’s regular menu.
Ray Kroc initially opposed adding the item because he wanted to keep the menu simple. A sales test compared Groen’s fish sandwich with a meatless alternative involving a pineapple dessert. The Filet-O-Fish performed better and was added to the menu.
The sandwich became an important example of local customer research influencing national branding. It is sometimes described as a company invention without mentioning Groen, but the product originated with a franchisee responding to the religious and regional habits of his customers.