Which McDonald's product introduced the “Filet-O-Fish” name in 1963?

The Filet-O-Fish sandwich introduced the “Filet-O-Fish” name at McDonald's in 1963.

McDonald's added the sandwich after franchisee Lou Groen developed a fish-based menu item for his Cincinnati restaurant. His location served a large Catholic population, and sales were especially challenging on Fridays when many Catholic customers avoided meat. The fish sandwich offered a way to attract those customers without abandoning McDonald's fast-service format.

The product became a permanent part of the menu and expanded McDonald's brand beyond hamburgers. It also became particularly associated with the period of Lent, when demand for meatless meals often rises.

The Filet-O-Fish is sometimes confused with later seafood promotions or with a generic fish sandwich. Its capitalized name is a specific McDonald's product brand dating to 1963.