Can Cats Eat Tuna? The Short Answer
Can cats eat tuna? Yes — plain, cooked tuna is safe for most cats as an occasional treat, and most cats absolutely love it. A small amount of tuna now and then is fine. But tuna should never become a regular part of your cat’s diet, and it should never replace a complete, balanced cat food. The reason is mercury. Tuna is a large predatory fish that accumulates mercury in its flesh, and cats are small animals — even a small amount of mercury exposure adds up over time. Regular tuna feeding can lead to mercury poisoning, nutritional deficiencies, and a condition called steatitis, or yellow fat disease. This guide explains exactly how much tuna is safe, which type of tuna is safest, the risks to watch for, and healthier fish alternatives your cat will enjoy just as much.
Why Cats Love Tuna (and Why That Is a Problem)
Cats are famously drawn to tuna. The strong smell, the soft texture, and the high protein content hit every button in a cat’s sensory system. In the wild, cats are obligate carnivores — they need meat, and their sense of smell is tuned to detect it. Tuna’s powerful aroma is irresistible to most cats, and many owners find that even the pickiest eater will come running for a spoonful of tuna.
The problem is that this enthusiasm can mislead owners. A cat that begs for tuna is not telling you that tuna is good for them — they are telling you that it smells amazing. Cats have no nutritional wisdom about human foods; they will happily eat things that are bad for them, from tuna to milk to raw fish. It is your job to decide what goes in the bowl. Tuna is fine as a treat, but it is not a food. A cat that eats tuna every day is a cat that is not eating the balanced diet they need, and that is where the real problems begin.
The Mercury Problem: Why Tuna Is Not an Everyday Food
The single biggest reason to limit tuna is mercury. Mercury is a heavy metal that accumulates in ocean fish, and the bigger and longer-lived the fish, the more mercury it carries. Tuna are large, long-lived predators that eat smaller fish, concentrating mercury at each step up the food chain. The US Food and Drug Administration (FDA) advises people to limit their own tuna consumption for exactly this reason — and cats, who weigh 8 to 12 pounds on average, are far more vulnerable to mercury exposure than a 150-pound human.
Mercury poisoning in cats is a real, documented condition. Symptoms include loss of coordination, tremors, difficulty walking, vision problems, and behavioral changes. It develops gradually, which makes it easy to miss until it is serious. A cat that eats tuna once a week in small amounts is unlikely to develop mercury poisoning. A cat that eats tuna every day — especially a large amount — is at genuine risk. This is not a theoretical concern; veterinary textbooks and case reports describe cats that developed mercury toxicity from tuna-heavy diets. The ASPCA’s cat nutrition guidance notes that fish, including tuna, should be an occasional food, not a dietary staple.
Not all tuna is equal when it comes to mercury. Light tuna (skipjack) contains significantly less mercury than white or albacore tuna. Canned light tuna in water averages about 0.12 parts per million of mercury, while canned white (albacore) tuna averages about 0.35 parts per million — roughly three times as much. If you are going to give your cat tuna, canned light tuna packed in water is the safer choice. Albacore tuna, fresh tuna steaks, and tuna sushi should be avoided or given very rarely and in tiny amounts.
Nutritional Deficiencies: Tuna Is Not a Complete Food
The second major problem with tuna is what it does not contain. Cats need a precise balance of nutrients — taurine, arachidonic acid, vitamin A, vitamin E, calcium, and more — and tuna does not provide them in the right proportions. A cat that fills up on tuna is a cat that is missing the nutrients in their regular food. Over weeks and months, this can lead to real deficiencies.
The most dangerous is vitamin E deficiency, which causes steatitis — inflammation of the fat tissue, also called yellow fat disease. Cats fed a diet heavy in oily fish develop painful, hard lumps under the skin, become lethargic, lose their appetite, and may develop a fever. Steatitis is painful and requires veterinary treatment, including vitamin E supplementation and a diet change. It is entirely preventable by keeping tuna as a rare treat rather than a regular meal.
Tuna is also high in unsaturated fatty acids and low in calcium relative to phosphorus, which can contribute to bone problems over time if it displaces balanced food. And tuna contains very little taurine relative to a cat’s needs — taurine deficiency can cause serious heart disease (dilated cardiomyopathy) and blindness in cats. Commercial cat foods are formulated with the right taurine levels; tuna is not. This is why veterinarians and the AVMA’s cat care resources consistently recommend feeding a complete, balanced commercial cat food as the foundation of your cat’s diet, with treats — including tuna — making up no more than 10 percent of daily calories.
How Much Tuna Is Safe? Portion Guide
For a healthy adult cat, a safe amount of tuna is a tablespoon or two of plain, cooked tuna — or a spoonful of canned light tuna in water, drained — once or twice a week at most. That is it. A tablespoon of tuna is roughly 15 to 20 calories, which fits comfortably within the 10 percent treat allowance for a cat eating 200 to 250 calories per day. Think of tuna the way you think of dessert for yourself: a small, occasional pleasure, not a meal.
For kittens, the limit is even stricter. Kittens are growing rapidly and need every calorie to come from balanced kitten food. A tiny taste of tuna — half a teaspoon — once in a while is fine, but do not make it a habit. Senior cats and cats with kidney disease should be especially careful, because tuna is high in phosphorus and sodium, which can worsen kidney problems. If your cat has kidney disease, ask your veterinarian before offering tuna at all.
If your cat has already been eating a lot of tuna — say, a can a day — do not panic, but do act. Stop the daily tuna immediately, switch back to a complete balanced cat food, and mention the tuna habit at your next vet visit. Your vet may want to check for signs of mercury exposure or vitamin E deficiency, especially if your cat shows any symptoms such as wobbliness, tremors, lethargy, or painful lumps under the skin. The sooner you correct the diet, the better the outcome.
Which Tuna Is Safe, and Which Should You Avoid?
Not all tuna products are equal. The safest choice is plain canned light tuna packed in water, drained before serving. It has the lowest mercury of the common options, no added oil, and no seasoning. Rinse it briefly under water to reduce sodium further. Avoid canned tuna packed in oil — the extra fat adds unnecessary calories and can cause stomach upset. Avoid tuna with added salt, flavorings, or sauces.
Never give your cat raw tuna. Raw fish can carry bacteria such as Salmonella and parasites, and raw fish contains an enzyme called thiaminase that destroys vitamin B1 (thiamine). Thiamine deficiency in cats can cause neurological symptoms, including loss of appetite, wobbliness, and seizures. Cooking destroys thiaminase, so plain cooked tuna is safe in this respect — raw is not. This is one of the reasons sushi-grade tuna and raw fish diets are a bad idea for cats.
Also avoid tuna cat treats and “tuna-flavored” products that list tuna as a minor ingredient alongside fillers — these are often high in sodium and low in nutritional value. And never give your cat tuna intended for humans that has been seasoned with garlic, onion, or spices. Garlic and onion are toxic to cats, even in small amounts, and can cause anemia. Plain is the only safe preparation.
Healthier Fish Alternatives Your Cat Will Love
If your cat loves fish, there are safer options than tuna. Salmon is an excellent choice — it is rich in omega-3 fatty acids, lower in mercury than tuna, and most cats love it. Cooked, boneless salmon, served plain and in small amounts, is one of the healthiest fish treats you can offer. Sardines are another great option: they are small fish with very low mercury levels, and they are packed with omega-3s and calcium (if served with the soft, edible bones). A single small sardine, packed in water with no added salt, is a perfect cat treat.
White fish such as cod or tilapia, cooked plain and boneless, is also safe in small amounts and is lower in mercury than tuna. And if your cat’s main interest is the smell and flavor rather than the fish itself, consider a commercial cat food or treat with fish flavor — these are formulated to be nutritionally balanced and safe for regular feeding, unlike plain tuna. Many US brands, including Fancy Feast, Blue Buffalo, and Wellness, make fish-flavored cat foods and treats that satisfy a fish-loving cat without the mercury risk.
Whatever fish you choose, the same rules apply: plain, cooked, boneless, unseasoned, and in small amounts as part of the 10 percent treat allowance. Fish should complement a balanced diet, never replace it. If you are unsure about your cat’s overall diet, your veterinarian can recommend a food that fits your cat’s age, weight, and health status — and they can tell you whether fish treats are appropriate for your individual cat.
If you share your home with both a cat and a dog, remember their nutritional needs are very different — what is safe for one is not automatically safe for the other. For example, our guide to whether dogs can eat bananas covers safe fruit portions for dogs, and our guide to how much to feed a puppy explains portion control that helps prevent overfeeding in multi-pet homes. Always feed each pet their own species-appropriate food, and keep the cat’s tuna treats well away from a curious dog.
What to Do If Your Cat Eats Too Much Tuna
If your cat gets into a can of tuna and eats the whole thing, do not panic — a single large serving is unlikely to cause mercury poisoning, which develops from repeated exposure over time. Watch for vomiting, diarrhea, or stomach upset over the next 24 hours, and offer plenty of fresh water. If your cat vomits repeatedly, refuses food, or seems lethargic, call your veterinarian.
The real concern is chronic overfeeding. If your cat has been eating tuna daily for weeks or months, stop immediately and switch to a balanced diet. Watch for the warning signs of mercury toxicity — loss of coordination, tremors, unusual behavior — and the signs of steatitis — painful lumps under the skin, lethargy, fever, loss of appetite. If you notice any of these, see your veterinarian promptly. Blood tests can check mercury levels, and your vet can prescribe vitamin E and a corrected diet if steatitis is diagnosed. Most cats recover well once the tuna is removed from their diet and proper nutrition is restored, but early action matters.
Frequently Asked Questions
Can cats eat tuna every day?
No. Tuna should be an occasional treat — a tablespoon or two, once or twice a week at most. Daily tuna feeding risks mercury poisoning and nutritional deficiencies, including vitamin E deficiency (steatitis) and taurine deficiency. Feed a complete, balanced commercial cat food as the main diet.
Is canned tuna safe for cats?
Plain canned light tuna packed in water, drained and rinsed, is the safest canned option because it has the lowest mercury level. Avoid tuna packed in oil, tuna with added salt or flavorings, and albacore (white) tuna, which has about three times the mercury of light tuna. Serve only a small amount as a treat.
Can kittens eat tuna?
A tiny taste — half a teaspoon — once in a while is fine, but kittens should get almost all of their calories from a complete, balanced kitten food. Kittens are growing rapidly and are more vulnerable to nutritional imbalances and mercury exposure, so keep tuna extremely limited.
Why is tuna bad for cats if they love it so much?
Tuna is not “bad” in small amounts — it is the frequency and quantity that cause problems. Tuna is high in mercury, low in essential nutrients like taurine and vitamin E, and can cause steatitis if fed regularly. Cats love the smell and taste, but they have no way to know it is nutritionally incomplete. It is your job to keep it as a treat.
What fish is safest for cats?
Small, low-mercury fish are safest: sardines, salmon, and white fish such as cod, served plain, cooked, and boneless in small amounts. These offer the omega-3 benefits of fish with far less mercury risk than tuna. Always serve fish unseasoned and as part of the 10 percent treat allowance, never as a meal replacement.