How McDonald’s Filet-O-Fish Became a Menu Staple

*In 1959, entrepreneur Lou Groen opened the first McDonald’s in the Cincinnati, Ohio area. After working a variety of jobs and eventually becoming president of the Cincinnati Restaurant Group, Groen partnered with McDonald’s founder Ray Kroc to launch his franchise. However, as Reader’s Digest reports, he soon faced a major challenge: about 87 percent of the local population was Catholic, and in the early 1960s, many Catholics abstained from eating meat on Fridays, except for fish. This tradition caused a sharp drop in sales during what should have been peak weekend hours.

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Inspired by the success of Big Boy restaurants, which offered a fish sandwich to attract Friday customers, Groen proposed a fried halibut sandwich with tartar sauce. Ray Kroc, skeptical of the idea, countered with his own creation: the “Hula Burger,” a peculiar mix of pineapple and cheese on a bun. To settle the debate, both sandwiches were tested on a single Friday, with Groen’s fish sandwich selling about 350 units. Kroc conceded defeat, admitting Groen had won the bet, and the “Hula Burger” joined the ranks of McDonald’s failed menu experiments.

To make the fish sandwich cost-effective, Groen and Kroc switched from pricey halibut to cod, adding a slice of cheese to maintain flavor. The revised sandwich, priced at 25 cents, became a hit, reviving Friday sales and securing Groen’s franchise. Though the recipe has evolved—now featuring sustainable Alaskan Pollock—the Filet-O-Fish remains a mainstay.

The sandwich’s popularity surges during Lent, when many Catholics abstain from land- and air-based meats, spokeswoman Becca Hary told USA Today.

Shrinkflation continues

American ordered a McDonald’s Filet-O-Fish sandwich and is shocked that they are now the size of a slider. Seriously, look at this… Americans are getting robbed blind pic.twitter.com/2OC53NPBcL

— Wall Street Apes (@WallStreetApes) August 20, 2025