A McDonald’s customer says they got more than tartar sauce with their Filet-O-Fish: a worm.
The bizarre surprise popped up in a Reddit post that included a photo of what the user described as a parasite sitting inside the sandwich. Cue the instant panic… followed by an even faster wave of commenters basically saying, relax, this happens.
“It’s pretty normal,” one person wrote, claiming it’s not dangerous because the fish is fried at high temperatures. Another commenter went further and identified it as an anisakid nematode, a type of roundworm commonly found in saltwater fish.
So what is it — and should anyone be worried?
The “worm” being discussed is typically linked to wild-caught fish like cod, halibut, flounder, and pollock. And yes, pollock is the fish used for McDonald’s Filet-O-Fish.
That’s the key point: wild fish can carry parasites. A parasite showing up can be gross to see, but it doesn’t automatically mean the food is unsafe — it can simply mean the fish came from the wild.
One food writer, Matthew Spina (Tasting Table), has explained that these parasites are basically unavoidable in wild-caught seafood and are “nothing to worry about” when the fish is properly cooked.
McDonald’s Filet-O-Fish patties are deep-fried, which means they hit temperatures high enough to kill parasites. In other words: disgusting-looking doesn’t equal dangerous.
The bigger risk comes from raw or lightly cooked fish that hasn’t been frozen or cooked enough to kill parasites — the kind found in dishes like sushi or ceviche. That’s where anisakiasis (a parasite infection) can become a real concern.
So what should you do if it happens to you?
If you bite into a Filet-O-Fish and spot something that looks like a worm:
- stop eating it (because… obviously)
- take a photo and keep the receipt if you have it
- contact the restaurant or McDonald’s customer service for a replacement or refund
Even if experts say the risk is low when the fish is cooked, most people don’t want to “unsee” that moment — and you’re well within your rights to ask for your money back.
