Cats and tuna have a relationship that goes well beyond typical food preference. Most cats will abandon whatever you put in their bowl the moment tuna enters the room. The smell alone tends to override everything else.
But the popularity of tuna among cats and the safety of feeding it regularly are two different questions.
Why Cats Love Tuna So Much
Cats are obligate carnivores — they require animal protein to survive, and their taste buds are wired to seek it out. Tuna is intensely aromatic, high in protein, and rich in amino acids cats are biologically driven to find appealing.
The smell comes largely from trimethylamine and other volatile compounds that develop when fish proteins break down. To humans, it ranges from pleasant to overpowering. To cats, it's essentially irresistible.
This is also why tuna becomes problematic: once a cat develops a strong preference for it, getting them to eat anything else can become genuinely difficult.
Is Tuna Safe for Cats?
In small amounts, yes. Plain cooked or canned tuna — in water, not oil — is not toxic to cats. Many commercial cat foods include tuna as an ingredient for good reason: it's nutritious, palatable, and a strong source of protein and omega-3 fatty acids.
The problems come with frequency and quantity.
The Risks of Too Much Tuna
Mercury accumulation. Tuna — particularly albacore (white tuna) — is high in mercury relative to most other fish. Cats are small, and mercury accumulates in body tissue over time. Regular high-tuna diets have been linked to mercury toxicity in cats, which presents as neurological symptoms: tremors, difficulty walking, loss of coordination.
Thiamine deficiency. Raw tuna contains an enzyme called thiaminase that destroys thiamine (vitamin B1). Cats need thiamine for normal nerve and brain function. A diet heavy in raw tuna can deplete thiamine over time, causing serious neurological problems. Cooked tuna has reduced thiaminase activity, but it's still a reason to limit intake.
Nutritional imbalance. Tuna doesn't meet a cat's complete nutritional needs. Cats require taurine, arachidonic acid, vitamin A in pre-formed retinol, and other nutrients that tuna doesn't provide in the right ratios. A cat eating mostly tuna is likely deficient in several key nutrients even if they seem healthy short-term.
Steatitis. Also called yellow fat disease, this is an inflammatory condition caused by excessive unsaturated fatty acids without sufficient vitamin E. It's associated with diets high in oily fish, including tuna. It's painful and can be serious.
The addiction problem. Tuna is palatable enough that some cats will refuse other foods once they've had it regularly. A cat that only wants tuna is a cat that's progressively harder to feed adequately.
How Much Tuna Is Safe?
Treat it as an occasional food — not a staple. A reasonable guideline: tuna as a treat or food topper no more than once or twice a week, in small amounts. A tablespoon or two for an average adult cat.
If you use it as a food topper to encourage eating, that's fine — just keep the portion small and the frequency moderate.
Which Type of Tuna Is Best?
Canned tuna in water — the best option if you're feeding it occasionally. Lower in fat than oil-packed, and no added sodium if you choose the "no salt added" variety.
Canned tuna in oil — not harmful in small amounts, but the added fat and calories aren't necessary.
Raw tuna — avoid due to the thiaminase issue and the risk of bacteria and parasites.
Tuna made for humans vs. cat-specific tuna: commercial cat food that contains tuna is formulated to be nutritionally complete. That's meaningfully different from serving plain canned tuna, which is not a balanced food.
What About Kittens?
The same guidance applies, with smaller portions. Kittens have higher nutritional demands during development, so a diet skewed toward any single incomplete food — including tuna — is more likely to cause deficiencies. Stick to kitten-specific food as the foundation and treat tuna as an occasional extra.
The Short Version
Tuna is safe for cats in moderate amounts — a few times a week at most, in small servings, as a treat or topper rather than a meal. The obsession cats have with it is real, but feeding it freely creates genuine health risks over time. Use it strategically and keep the rest of their diet nutritionally complete.