Can cats eat raw fish?

You’ve just sat down to your favorite Door Dash supper from that yummy sushi restaurant in town and your cat is waiting expectantly as you reach into the bag. You can almost see the thought bubble above her head: “Sushi? I like sushi, too.”

And why not share? She’s a cat and cats eat fish. What’s the harm of a sliver of raw salmon or tuna?

It seems to defy logic, but cats should not eat raw fish, and not only for the reasons you might be thinking.

Cooked fish? Yes. Raw fish? No.

Don’t feed your cat any raw fish. Not a nibble. Not a bite. Let me explain why.

Don’t cats need to eat fish?

Fancy Feast Seafood Classic Pâté. Tiki Cat Seafood Selects. Orijen Six Fish Recipe. Commercial pet food preparations would have you believe otherwise, but cats really don’t eat fish in the wild.

Cats are obligate carnivores, which mean they are obligated to eat animal flesh to survive. Unlike dogs, who are omnivores and can do well eating a wide range of foods, including fruit, vegetables, grains, and meats, cats cannot survive on a vegan or vegetarian diet. It’s all animal protein, all the time.

But the kind of animal protein that cats eat in the wild eat is not usually fish. Cats evolved from desert-dwelling ancestors, and where there is no water, there is no fish.

Cats mostly eat birds and small mammals, like voles, mice, and rats. Also, given the opportunity, cats will eat lizards, snakes, frogs, and big insects. But fish is not a cat-diet staple.

So, cats don’t need to eat fish at all.

What’s wrong with fish?

There’s nothing wrong with fish as a source of animal protein, so long as it’s cooked. In fact, cooked fish is an excellent source of omega-3 fatty acids, which are essential nutrients for both cats and humans.

I explain all about fatty acids, why they’re necessary for good health, and even why they’re called “essential” in this post about giving fish oil to your cats.

If fish is so great for health, what’s wrong with raw fish?

Cooking causes a lot of magical changes to happen to fish flesh. It turns a food that is dangerous for cats to eat into one that is healthful.

Let’s discuss all the things that are wrong with raw fish, one by one.

Raw fish contains a dangerous enzyme called thiaminase

Raw fish contains an enzyme called thiaminase. This enzyme destroys the essential B vitamin thiamine.

Cats need thiamine for their brains to function, for the health of their nerves, and for appetite regulation. Having too little thiamine can lead to:

• Weakness
• Lethargy
• Difficulty walking
• Seizures and convulsions.[1]

Cooking destroys the thiaminase enzyme in fish completely. The risk of neurological problems from eating uncooked fish goes away the minute the fish is cooked.

If thiaminase is so dangerous, how can humans can eat sushi?

Cat biology and metabolism differs from humans and other animals in important ways.

Cats have an unusually high requirement for thiamine. In fact, a cat needs triple the amount of thiamine as a dog.[2] Cats also have a very limited ability to store thiamine compared to other animals.[3]

These two factors make them extra sensitive to the loss of thiamine that occurs when they eat raw fish.

Humans don’t tend to eat enough raw fish at one time to deplete all our reserves. And, unlike cats, people can get thiamine from other sources. We tend to eat a varied diet that includes thiamine-containing foods like grains and legumes.

Raw fish can contain parasites

Parasites are organisms that live on or inside an animal of another species, getting nutrients from their host. It’s estimated that 40% of all the animal species on the planet are parasites and that almost every animal on Earth is a host to multiple parasites.[4]

Just because parasites are ubiquitous doesn’t mean you want them in your body or your cat’s body. Parasites steal nutrition, damage tissue, and cause infection and disease.

No raw freshwater fish, ever

To start with, you never want to eat or feed your cat raw freshwater fish because they can contain tapeworms. Tapeworms can literally grow to 30 feet long inside of you or your cat, and migrate to bodily organs, including the brain.[5]

This warning also applies to fish like wild salmon that spend part of their lives in the ocean and part of their lives in fresh water. Farmed salmon does not tend to have this risk.

Isn’t sashimi or sushi-grade fish safe?

“Sashimi-grade” and “sushi-grade” are just marketing terms. There are no governing bodies grading fish. Anybody can call their fish sashimi-grade or sushi-grade if they want to.[6]

Doesn’t freezing kill parasites?

Freezing does kill parasites, but not the kind of freezing you’re thinking about. The FDA details the exact time and temperature at which various wild fish species need to be frozen to kill parasites but recommended temperatures go as low as -31°F. No home freezer can achieve temperatures that low.

But every state has its own regulations about freezing fish that is to be sold to be eaten raw and enforcement of these regulations varies between states, too. So, a regulation on the books doesn’t necessarily protect you or your cat.

Tuna and farmed salmon (so long as it has been fed parasite-free food) are exempt from FDA regulations regarding freezing because there have been relatively few documented cases of parasitic infections from eating them.

Do saltwater fish have parasites?

The most common kind of parasites found in marine fish are anisakids, which include nematodes and roundworms.

The problem with anisakids is that if they end up in your gut, or your cat’s gut, they know they don’t belong there. Anaskids can only complete their lifecycle in the bodies of fish-eating marine mammals and can do an awful lot of damage trying to find their way back home. They can get stuck as they burrow into your intestines or your cat’s intestines.[7]

Another parasite to worry about in raw marine fish is Nanophyetus salmincola, which is a fluke that causes salmon-poisoning disease. Even farmed salmon, particularly farmed salmon raised in open-net pens in the Pacific Northwest, can be infected.[8]

Yuck.

Raw fish can contain bacteria

Parasites may sound gross and horrible (and they are), but an even more serious problem with raw fish is bacteria.

Raw fish can contain Salmonella, E. coli, Listeria, and Campylobacter, all of which can cause severe gastrointestinal distress, including diarrhea, vomiting, fever, pain, and weight loss and lead to death. They can also pass these bacterial infections on to you.

Bacteria multiply in raw fish when it’s kept at unsafe temperatures for too long, or when it’s mishandled. Unfortunately, it’s surprisingly easy to “temp-abuse” raw fish.

Every species is different, but most fish need to be kept continuously below 40°F with minimal handling to prevent the growth of bacteria.

How to prepare fish for your cat to eat

(*Note: as an Amazon Associate, I may earn from qualifying purchases.)

You cat can absolutely enjoy fish, so long as it’s cooked.

First remove all of the bones.

Fish bones are small and sharp and can puncture the mouth, throat, or digestive tract. They can become a choking hazard if they get stuck in the throat and they can cause intestinal blockages that may require emergency life-saving surgery.

Avoid all seasonings, especially garlic or onions, which are toxic to cats. Avoid adding salt, too, which can cause high blood pressure, dehydration, and even salt poisoning (you didn’t know that was a thing, did you?).

Cook the fish thoroughly. You can boil, bake, grill, or sauté the fish.

Alternatively, you can buy one of these products for your cat. They are real, cooked, fish fillet portions that are very safe and very convenient to feed as a treat. I have bought them myself!

Inaba Premium Hand-Cut Grilled Tuna Fillet

Applaws Whole Mackerel Loins

Reveal Whole Salmon Fillet

Fish is a treat, not a meal for cats

No matter how carefully you cook and prepare fish for your cat to eat, it should be served as a treat, not a meal. There are three main reasons why:

Fish alone is not enough

Even though cats are obligate carnivores, they risk becoming nutrient-deficient eating just one kind of animal flesh. Commercial cat food diets contain added essential nutrients like calcium, taurine, and vitamins in the right proportions for cat health.

There’s such a thing as too much of a good thing. Too much fish can actually deplete a cat’s vitamin E levels causing inflammation in fatty tissue beneath the skin.

High fish diets have been associated with hyperthyroidism in cats, too, due to the high levels of iodine in fish, although that link is still being debated. [9]

Fish contains heavy metals

Unfortunately, fish flesh is a repository for all of the bad things we’ve put in our oceans.

These include mercury, which is especially prevalent in large fish like tuna and mackerel, toxic chemicals like PCBs and dioxins, and heavy metals such as arsenic.[10]

Some cats are allergic to fish

A large percentage of cats with allergies are allergic to fish. In a small study of allergic cats, fish was at least partially responsible for reactions in 23% of them.[11]

This is not to say that you should never feed fish, or fish-based commercial diets to your cats (unless you know that your cat is allergic to fish), but to remind cat guardians to never feed raw fish and only feed cooked fish as a special treat.

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Dawn LaFontaine

Dawn LaFontaine is a lifelong animal lover who always seems to have a little pet hair in her keyboard. Her blog, Kitty Contemplations, helps cat guardians better understand and care for the special beings they share their lives and homes with, and is a Top 10 cat blog on Feedspot. Her cat-products business, Cat in the Box, sells beautiful, well-made, and award-winning products that she designed to meet the biological needs of cats.