Facts About McDonald's Filet-O-Fish Sandwich You Didn't Know

The sandwich originated when franchise owner Lou Groen thought of the dish for customers at his Cincinnati-based location, which was predominantly Catholic.

Catholics weren't allowed to eat meat on Fridays at the time, so the Filet-O-Fish sandwich served as an alternative to hamburgers for the community.

Groen's new sandwich idea had a contender in McDonald’s president Ray Kroc's Hula Burger, a fried pineapple slice topped with cheese on a hamburger bun.

McDonald’s released both burgers together to see which one sold better. The Filet-O-Fish won the duel, selling 350 units compared to the Hula Burger's six.

The Filet-O-Fish has its own equipment and way of being prepared, using a separate fryer to keep the seafood flavor from being added to other menu items.

It's also the only permanent McDonald's menu item with a steamed bun. A Quora user with restaurant experience thinks the bun is steamed because it absorbs the tartar sauce better.

The sandwich is frequently listed among the healthiest items you can order at McDonald's. Fish is nutrient-rich, though frying makes it a bit less nutritious.

Since you can customize your Filet-O-Fish order, you can have it without cheese or tartar sauce to reduce calories and sodium. Plus, it's a menu item with the least sodium content.

The Filet-O-Fish has been made with real fish from the start. Groen made the prototype sandwich with halibut, but the fish used has changed over time.

Today, it's made from Alaskan pollock in most locations and is likely sourced from a sustainable fishery. The sandwich has been using sustainable fish since 2013.