Can Cats Eat Tuna in Water?

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Can cats eat tuna in water?


However, limit your cats tuna intake to only 1/2 tin of tuna per week.

The advised limit for humans is 3 tins (3 ounces) pet week which equates to a very small tolerable dose for cats.

Many point to the risk of mercury poisoning and steatitis with tuna intake. There’s also concerns cats choking on small bones found in raw tuna.

Are these fears based in reality? Is it all doom and gloom for tuna?

If you are unsure about whether tuna in water is cat friendly, read on to learn more.

I am a cat enthusiast and independent writer. I recommend seeking the advice of a vet for any further questions. The advice in this article is not intended as medical advice.

Can cats eat tuna in water?

Can Cats Eat Tuna in Water?


However, limit your cats tuna intake to only 1/2 tin of tuna per week.

Tuna contains mercury, a mineral that builds up and causes problems with movement.

Health authorities suggest people limit tuna to 3 small tins (85g) per week.

Since humans are much bigger than cats, it’s easy to see how their tolerance is higher.

Another problem with tuna is the polyunsaturated fat content. In high amounts causes dry skin, loss of appetite and depression.

Not satisfied?

Let’s look at some more info on tuna…

A cat with a tuna of tuna in water
Canned tuna is high in mercury, a metal which builds up in the body and can cause harm

What is Tuna?

Tuna is a large deep water fish.

When I say large…these things can grow in excess of 1,000 pounds.

Tuna feasts on seafood including:

  • Squid
  • Shellfish
  • Plankton

The most popular types of tuna farmed for human consumption are skipjack, albacore, and yellowfin.

Tuna swimming in the ocean
Tuna are a large fish that are high on the food chain.

Mercury Poisoning in Tuna

Mercury is a metal, like iron and zinc.

It is an environmental waste, formed from volcanoes or coal power plants.

Mercury is not metabolized.

Small fish consume mercury, and big fish (like tuna and sharks) eat small fish. This is why mercury builds up through the food chain.

A coal power plant
Mercury is an environmental contaminant

How Much Tuna is Bad for Cats?

Even one small tin of tuna is too much for a cat.

According to the Environmental Protection Agency, the safe limit to mercury is 0.1 mcg per kg.

Assuming the average cat is 5kg this equates to 0.5 mcg.

An 85g tin of light tuna contains 10 mcg of mercury. Oh no….

This is the lowest mercury tuna. Albacore and yellowfin have much more.

Based on this, it’s hard to see a place for tuna in the diet for your cat.

A tin of tuna.
A 85g tin of light tuna contains 10 mcg of mercury. This far exceeds what is probably safe for cats to eat on a daily basis.

What Happens When Cats Eat Too Much Tuna?

Cats are at risk of developing mercury poisoning when they eat tuna in water.

Mercury (technically methylmercury) builds up in the tissues and can cross the blood brain barrier into the brain.

A 1988 study gave kittens compared a diet of red tuna to beef. The tuna gave about 0.55 ppm mercury (~50 mcg).

When given tuna for 188 days, cats developed impairments in:

  • Vocalization
  • Movement
  • Playing
  • Jumping

The cats were euthanized, so it’s not known if recovery was possible.

A cat playing
Mercury toxicity can affect a cats desire to play and socialize

Are There Any Other Problems With Tuna?


Tuna is low in calcium.

Cats given a diet without calcium suffer neurological impairments, which can result in euthanasia.

Red tuna and other fatty fish are also high in polyunsaturated fats.

This type of fat can also build up in tissues and cause problems. This includes:

AAFCO recommend limiting PUFA in a cats diet, and supplementing vitamin E in high PUFA diets.

PUFA increases vitamin E requirement.

One case study documented the occurrence of pansteatitis from a fish only diet. It caused fever, pain in the abdomen, and hypersalivation.

Frequently Asked Questions

What’s the Canned Tuna Nutrition?

Canned tuna is a very high protein food that is low in total fat. It contains no carbohydrate.

Is Canned Tuna in Water Good for Cats?


Canned tuna contains too much mercury which is a health risk to cats.

Tuna is high in protein, but it doesn’t have the full range of nutrients cats need.

By itself, tuna isn’t a complete meal.

Is It Ok for Cats to Eat Tuna?

There’s no guidelines for cats.

In very small amounts, tuna is ok for cats (less than 1/2 of a 3 ounce tin per week).

In humans, research recommends no more than 4 tins per week.

Given cats are ~10% the weight of humans this equates to half a tin of tuna per week.

Not much at all!

As I am not a vet, I can’t give a precise amount but I’d keep the tuna at or under this amount to be cautious.

How Much Tuna Can You Give a Cat?

I don’t recommend giving your cat any more than half a tin per week.

There’s a lot of tuna based cat foods. Most of these use a variety of ingredients, but I’d suggest rotating different flavors.

Limit the tuna based cat food as much as possible to keep your cat safe.

Why Do Cats Like Tuna?

Cat’s love tuna and other fish due to these foods being high in protein.

Studies show that cats prefer high protein diets high in essential amino acids.

Recently, it’s been found cats have taste receptors for umami flavors (high in tuna) and histidine (also high in tuna).

Cats may have developed a taste for tuna feeding on scraps during the middle-ages.

What Fish Is Good for Cats?

Low mercury fish is the best choice for cats. This includes:

  • Flounder
  • Tilapia
  • Sole
  • Freshwater trout

Limit fish high in PUFA.

This type of fat builds up in a cats body and can cause harm (e.g. dry skin). Fish like mackerel is worth limiting.

What Human Food Can Cats Eat Daily?

Most food humans eat contains a wide array of ingredients. Some popular condiments, marinades, and spices are off limits for cats.

This includes things like:

  • Garlic
  • Onions
  • Chocolate
  • Mint
  • Tomatoes
  • Fruit
  • Spices

Unmarinated and seasoned cooked meat may be an option for cats.

Learn More:

What Are the Signs of Mercury Poisoning in Cats?

If your cat has eaten too much tuna, the can experience the following:

  • Impaired movement
  • Lack of play
  • Lack of vocalization

Putting cats on commercial cat food balanced for all life stages is a must.

This helps provide cats the missing nutrients in their diet.


Tuna is a high mercury large ocean fish. The amount of mercury in a small tin of tuna in water is too high for cats.

I recommend avoiding tuna and choosing low mercury seafood for your cats diet. This includes tilapia, and sole. Cat food with tuna is best as an occasional treat only.

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I'm qualified dietitian that's turned their attention to cat nutrition. My goal is to help tease out the science on how best to feed your cat.