The Filet-O-Fish was invented by McDonald’s franchisee Lou Groen and became a key fish-related brand.
Groen operated a McDonald’s restaurant in Cincinnati, Ohio, where many customers observed meatless eating practices on Fridays. He developed a fish sandwich to attract those customers while preserving McDonald’s fast-food format.
McDonald’s introduced the Filet-O-Fish nationally in 1963. The sandwich used a fried fish fillet, a steamed bun, tartar sauce, and cheese. Its distinctive hyphenated name made it immediately identifiable as a McDonald’s product rather than a generic fish sandwich.
The item is often linked only to religious observance, but its marketing and sales also helped McDonald’s reach customers who wanted a seafood alternative. It remains one of the company’s longest-running named menu products.