Can cats eat tuna?
Safe in moderationMost cats love tuna, but it should be a rare treat — too much causes mercury, nutritional, and 'tuna addiction' problems.
Reviewed by the Webvet Veterinarian Team · Last reviewed June 26, 2026
Can Cats Eat Tuna?
Cats can eat tuna, but only as a rare treat, never as a regular meal or a stand-in for balanced cat food. A small spoonful of plain tuna packed in water is not toxic, and most cats find it irresistible. The problem is what happens when tuna becomes a habit: human tuna is not nutritionally complete for a cat, and feeding it often can lead to mercury buildup, a painful vitamin E deficiency called steatitis, and picky eaters who refuse their real diet. Think of tuna as an occasional garnish, offered no more than about once a week, and you can share it safely.
- 1Tuna is safe in tiny amounts but is not a complete food for cats.
- 2Choose plain tuna packed in water, drained, with no salt, oil, or seasoning.
- 3Keep servings to about a teaspoon to a tablespoon, no more than once a week.
- 4Frequent tuna can cause mercury buildup, steatitis (vitamin E deficiency), and fussy 'tuna junkie' habits.
- 5Never feed tuna with onion, garlic, mayo, or heavy brine.
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Is Tuna Safe for Cats?
Tuna is not poisonous to cats, and a lick or a small flake now and then will not hurt a healthy adult. Cats are obligate carnivores, which means they are built to run on animal protein, so the meaty, fishy pull of tuna makes perfect sense to them. Tuna does offer protein, omega-3 fatty acids, vitamin B12, and selenium. If tuna were a complete feline food, it would be a great one.
The catch is that tuna is not balanced for a cat. It is missing key nutrients cats need in the right ratios, including taurine in adequate amounts, calcium, and vitamin E. A cat that fills up on tuna eats fewer of the nutrients it actually needs, and over weeks and months that gap becomes a real health problem. So the honest answer is that tuna is safe to share in tiny amounts, but it is a treat, not nutrition. That single distinction is what keeps tuna on the right side of safe.
How Much Tuna Can a Cat Eat?
Portion is everything with tuna. A cat weighs only about eight to ten pounds, so a serving that looks tiny to you is already a lot to a cat. As a rule, keep tuna to roughly a teaspoon up to a tablespoon at a time, and offer it no more than about once a week. Treats of any kind should make up no more than ten percent of a cat's daily calories, and the rest should come from a complete, balanced cat food. Tuna sits inside that small treat budget, not on top of it.
Kittens should get even less, or none at all. Growing kittens have precise nutritional needs, and a strong-tasting food like tuna can push them off their balanced kitten diet at the worst possible time. If you want to share a taste with a kitten, keep it to a single tiny flake and only occasionally. When in doubt, skip it and reach for a proper kitten treat instead.
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| Tuna type | Cat-safe? | Why |
|---|---|---|
| Plain tuna in water, drained | Occasional treat | Lowest salt and fat; best option, still only rarely |
| Tuna in oil | Avoid | Too much fat; can cause stomach upset and adds empty calories |
| Tuna in brine or salted | Avoid | Cats are very sensitive to salt; too much strains the kidneys |
| Raw tuna | Avoid | Parasite risk and an enzyme that destroys thiamine (vitamin B1) |
| Tuna with mayo, onion, or garlic | Never | Onion and garlic are toxic to cats; mayo adds fat and additives |
The Risks of Feeding Cats Too Much Tuna
The dangers of tuna are almost all about quantity and frequency. A tiny taste is harmless, but three specific problems show up when tuna becomes a regular feature of a cat's diet, and they are worth understanding before you make it a routine.
Mercury buildup. Tuna is a large, long-lived fish that accumulates mercury from the ocean. A cat's small body means mercury can build up faster than you might expect with frequent feeding. Chronic mercury exposure can affect the nervous system, causing signs like loss of coordination or unusual behavior over time. This is why tuna should stay an occasional treat and never a daily food.
Steatitis, or yellow fat disease. Tuna is high in unsaturated fatty acids but low in vitamin E. A diet heavy in tuna can lead to a vitamin E deficiency that causes steatitis, a painful inflammation of the body's fat. Affected cats become sore to the touch, lose their appetite, and can become seriously ill. It is a classic consequence of an all-tuna or tuna-heavy diet and is entirely preventable by keeping tuna rare.
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Tuna addiction. Cats can become genuine 'tuna junkies.' The strong smell and flavor are so appealing that some cats start refusing their balanced food and hold out for tuna instead. That fussiness sets up exactly the nutritional imbalance you are trying to avoid, because a cat living on tuna misses the taurine, vitamins, and minerals a complete diet provides. Once a cat is hooked, weaning it back onto proper food can be a real battle.
Raw, Canned, and Flavored Tuna: What to Watch For
Not all tuna is equal. Raw tuna is best avoided entirely: it can carry parasites and contains an enzyme called thiaminase that destroys thiamine, a B vitamin cats need, which can lead to a serious deficiency. Cooking deactivates that enzyme, so if you share fish, share it cooked and plain. Canned tuna in water is the most reasonable choice, but only when it is drained and unsalted.
Skip tuna packed in oil, which adds far too much fat, and skip tuna in brine or with added salt, since cats are highly sensitive to sodium. Anything flavored, such as tuna with mayo, onion, garlic, or seasoning, is off the table, because onion and garlic are toxic to cats in even small amounts and are more dangerous to them than to dogs. There is also cat-specific tuna sold as a treat; it is formulated to be safer than the human kind, but the same rule applies, which is to offer it sparingly.
Safe Treat Alternatives to Tuna
Because cats are carnivores, the best treats are meaty rather than sweet or starchy. If you want to give something special without the tuna baggage, try a little plain cooked chicken, a small amount of plain cooked egg, or a bite of plain cooked white fish. Fatty fish like salmon and small oily fish such as sardines are also good occasional options when served plain and boneless. All of these give a cat the animal protein it craves without the mercury load or the addictive pull of tuna.
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You can also lean on treats made for cats: a lick of plain meat baby food with no onion or garlic, freeze-dried meat treats, or a proper commercial cat treat. Whatever you choose, keep it to a small taste and remember that a complete, balanced cat food should always do the heavy lifting. Treats, tuna included, are just the fun on top.
Frequently Asked Questions
Frequently Asked Questions
How much tuna can I give my cat?
Keep it to about a teaspoon up to a tablespoon of plain tuna in water, drained, no more than about once a week. Tuna should stay within the small treat share of your cat's diet, which is no more than ten percent of daily calories, with balanced cat food providing the rest.
Is canned tuna okay to feed my cat?
Only canned tuna packed in water, drained and unsalted, and only as an occasional treat. Avoid tuna in oil or brine, and never feed tuna that has been mixed with mayo, onion, garlic, or seasoning. Canned tuna is not a complete food, so it cannot replace your cat's regular diet.
Can cats eat tuna every day?
No. Daily tuna is one of the fastest ways to cause problems, including mercury buildup, vitamin E deficiency and steatitis, and a fussy 'tuna junkie' who refuses balanced food. Tuna should be a rare treat, not a daily food.
Can kittens eat tuna?
It is best to skip tuna for kittens, or offer at most a single tiny flake very occasionally. Kittens have precise nutritional needs for healthy growth, and a strong-tasting food like tuna can put them off the balanced kitten diet they depend on. A proper kitten treat is a safer choice.
Can cats eat raw tuna?
No, avoid raw tuna. It can carry parasites and contains an enzyme called thiaminase that destroys thiamine, a B vitamin cats need, which can cause a serious deficiency over time. If you share fish, it should be plain and fully cooked.
Sources
Reviewed by the Webvet Veterinarian Team
General guidance based on credible veterinary sources — not a diagnosis or a substitute for your veterinarian. If your pet ate something toxic or is unwell, contact your vet or a pet poison line right away.