[3] It was created in 1962 by Lou Groen, a McDonald's franchise owner in a predominantly Catholic neighborhood of Monfort Heights in Cincinnati, Ohio,[4][5] in response to declining hamburger sales on Fridays due to the practice of abstaining from meat on that day.

[9] In 1981, when an owner of a New Zealand fisheries company was dissatisfied with the pollock Filet-O-Fish he purchased at the Courtenay Place, Wellington restaurant, he said to the manager that he could make a better-tasting fish fillet.

The similar-tasting hoki was substituted several years later, due to its competitive market value and its boneless fillets, and eventually was introduced widely in the early 1990s when global pollock stocks were facing low numbers.

[13] As of March 2009, the Marine Stewardship Council[14] placed the Alaska pollock fisheries in a re-assessment program[15] due to catch numbers declining by over 30% between 2005 and 2008, and by-catch problems with salmon.

As of January 2013, the Marine Stewardship Council stated that the pollock comes from suppliers with sustainable fishing practices, and McDonald's packaging and promotion will reflect that change.

[36][37][38] The Filet-O-Fish, originally created for Western Christians observing the Friday Fast, remains popularly associated with this community, with US sales significantly rising around Lent.

[39] This sandwich is also popular among Jewish and Muslim communities due to its ingredients being more aligned with kashrut and halal rules than McDonald's other offerings.