Filet-O-Fish was the McDonald’s product name created for a fish sandwich introduced in 1962.
The sandwich was developed by Lou Groen, a McDonald’s franchise owner in Cincinnati, Ohio. His restaurant served a neighborhood with many Catholic customers, and sales traditionally weakened on Fridays when some customers avoided meat. Groen proposed a fish sandwich to broaden the restaurant’s appeal on those days.
The Filet-O-Fish became a lasting part of McDonald’s product branding. Its name combines “filet,” referring to the fish portion, with “O-Fish,” a playful construction associated with the chain’s naming style. The product was initially tested before becoming part of the wider menu.
The sandwich is often discussed alongside the Big Mac and McChicken, but it predates both the McChicken and many later specialty sandwiches. Its branding is important because it shows McDonald’s adapting its menu and product names to regional customer habits.