The Short Answer
Yes, but carefully. Most cats go absolutely wild for tuna — the smell alone can bring them running from three rooms away. A small amount of plain tuna as an occasional treat is perfectly fine. The problems start when "occasional" turns into "every day" or when tuna starts replacing balanced cat food.
Why Cats Love Tuna So Much
Cats have a strong affinity for tuna because it hits all their flavor receptors at once: it's high in protein, rich in fat, and has a potent umami taste. Cats are also drawn to the amino acid profile and strong aroma of fish. This is exactly why tuna can become a problem — some cats will literally refuse to eat anything else once they develop a taste for it.
The Risks of Too Much Tuna
Mercury Accumulation
Tuna is a large predatory fish that accumulates mercury through the food chain. This is the biggest long-term risk. Cats are small animals, and regular tuna consumption can lead to mercury levels that cause neurological problems over time. Symptoms of mercury toxicity include loss of coordination, difficulty walking, and vision changes.
Tuna Addiction
This sounds like a joke, but veterinarians take it seriously. Cats can become so fixated on tuna that they refuse all other food — including nutritionally complete cat food. This leads to malnutrition, because tuna alone doesn't meet a cat's needs. It lacks adequate vitamin E, calcium, and other nutrients essential for feline health.
Thiaminase in Raw Tuna
Raw tuna contains an enzyme called thiaminase that destroys thiamine (vitamin B1). Thiamine deficiency in cats can cause serious neurological symptoms, including seizures. This is another reason cooked or canned tuna is always preferable to raw.
Steatitis (Yellow Fat Disease)
A diet too heavy in unsaturated fish fat (like tuna) without enough vitamin E can cause steatitis — a painful inflammation of body fat. It's rare with occasional feeding but a known risk in cats eating fish-heavy diets.
How to Safely Share Tuna
- Canned tuna in water is the safest option — skip tuna packed in oil (too much fat) or with added salt
- Limit to 1–2 teaspoons, once or twice a week at most
- Use it as a food topper to entice a picky eater, not as a standalone meal
- A spoonful of tuna water drizzled over dry food can add flavor without overloading on fish
- Never serve raw tuna to your cat
- Rotate with other protein treats — don't let tuna be the only special thing
The Bottom Line
Canned tuna in water scores 72 on our safety scale — in the Generally Safe — Good snack tier. As an occasional treat, it's fine and most cats will adore you for it. But respect the limits: mercury is real, tuna addiction is real, and your cat needs a balanced diet to thrive. Think of tuna as the feline equivalent of fast food — delicious, but not dinner every night.