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Is Fish in Cat Food Bad for Cats? Maybe More Than You Think

Fish can produce large amounts of histamines after being caught, which can be bad for cats.

Lisa Richman  |  May 12th 2016


For anyone with allergies, the word antihistamine dredges up images of over-the-counter medicines we wouldn’t want to live without. All those pills, sprays, creams, and eye drops give us relief from whatever we’re allergic to: pollens, peanuts, even puppies.

The very word antihistamine implies that histamine is a bad thing. Break it up into its component parts and you have anti plus histamine. Evidently whatever histamine is, we’re very against it.

Woman suffering from pollen allergies.

Many of us experience histamine reactions all too frequently! A woman sneezes by Shutterstock

Surprisingly, though, histamine is not all bad. In fact, we can’t really live without it. It plays a very important role in our body’s defensive arsenal: It helps usher white blood cells to the tissues in your body to ward off infection.

Unfortunately, it also causes a lot of side effects, like stuffy noses and watery eyes. We humans aren’t the only creatures who experience this, either. Other mammals including cats and dogs experience histamine reactions — more commonly called allergic reactions — too.

Fish have histamine reactions, too. And that can be a big problem for your cat.

To be honest, I have no idea whether fish are actually allergic to anything. Nor whether they experience the aquatic version of a runny nose. But I do know they produce histamine. They’re also a major ingredient in most cat foods. And that’s what makes it problematic.

Black cat scores a fish!

Fish is in a surprising amount of cat food. A cat holds a fish by Shutterstock

You see, there’s this really weird thing that happens to some fish after they’ve been caught. They actually begin making histamine. A LOT of it. So much, in fact, that improperly preserved fish can give your cat (and you) a severe case of histamine poisoning.

It’s a condition known as scombroidosis.

The symptoms of scombroidosis can include nausea, vomiting, diarrhea, headache, fever, flushed skin, and a rapid pulse rate. Several years ago a family in Albuquerque — as well as the family dog — experienced this firsthand when they ordered mahi for dinner at a restaurant … and brought home the proverbial doggie bag.

A trip to the emergency room for the humans, and to the emergency vet for the dog, resulted in a diagnosis of scromboidosis.

Dr. Phil Lieberman of the American Academy of Allergy, Asthma, and Immunology tells us that scromboidosis or scombroid poisoning “is unique among the seafood toxins since it results from product mishandling rather than contamination.”

orange moggy stares hungrily at goldfish in bowl.

Cats might like fish in their food, but it doesn’t necessarily like them. A cat looks at a goldfish by Shutterstock

It’s caused, he explains, when fisherman have inadequate cooling procedures in place while harvesting and storing the fish they catch. If the fish aren’t immediately put on ice, a “bloom effect” occurs, resulting in a release of bacterial histamine.

Excessive amounts of bacterial histamine, he says, cause “an allergy-like form of food poisoning” that continues to be a major problem in seafood safety today.

What can you, as a cat owner do? Become your cat’s consumer advocate. Opt for formulas that do not include seafood in them. And read your cat food labels. Many cat foods labeled as containing other proteins have fish as secondary ingredients.

Cat looks pleadingly at camera, wants to eat fish.

Some cats have very strong opinions on seafood. A cat and a fish by Shutterstock

And if your finicky feline insists on a surf-and-turf diet, choose carefully. Go with brands that are known for quality, or better yet, human-grade ingredients. You are the only advocate your cat has, and he depends upon you for his health and well-being.

Does your cat insist upon a seafood diet? Has this article changed your opinion on seafood-based cat foods? Let us know in comments.