Can Cats Eat Tuna? What's Safe and How Often

Yes, most healthy cats can eat a small amount of plain canned tuna as an occasional treat. Tuna should not be a daily food or a meal replacement, because it is not a complete diet for cats and it carries mercury.

Key takeaways

Tuna is fine as an occasional treat, not as a regular meal.
Choose canned chunk-light tuna in water. Skip albacore, which is higher in mercury.
Avoid tuna packed in oil and raw tuna.
A diet made up only of tuna can cause thiamine (vitamin B1) deficiency.
Cats offered tuna often can start refusing their regular food.

Is tuna safe for cats?

In small amounts, yes. A veterinary nutritionist at Tufts University’s Cummings School advises keeping tuna to an occasional treat and choosing canned chunk-light tuna. Albacore comes from a larger species of tuna and has mercury levels almost three times higher.

The same nutritionist notes she has not seen a report of mercury poisoning in a cat fed tuna-based commercial cat food. She also points out that there is little data on mercury levels in cats, which is why moderation is the safer course.

Why can’t cats eat tuna every day?

It is not a balanced diet. A diet made up only of fish like tuna leads to thiamine deficiency, which can cause serious brain damage.
Mercury adds up. A cat eating tuna as its main diet takes in far more mercury for its body weight than a person who eats a lot of tuna.
Cats get hooked. Some cats like tuna so much that they turn down their regular food and become picky eaters. They may also gain weight.

Which kind of tuna is best for cats?

Type of tuna	OK for cats?	Why
Canned chunk-light in water	Yes, as an occasional treat	Lower in mercury than albacore
Albacore (white) tuna	Best avoided	Mercury levels almost three times higher
Tuna packed in oil	No	Rich, and can upset digestion
Raw tuna	Best avoided	Can upset the stomach, and raw fish contains an enzyme that breaks down thiamine
Complete cat food made with tuna	Yes	Formulated to be nutritionally balanced

How much tuna can a cat have?

There is no single agreed safe amount. Treat tuna the way you would any treat: a small portion now and then, not a daily habit. If your cat has a health condition, ask your vet before adding tuna at all.

If your cat already eats a tuna-based cat food, that counts too. One option is to switch to foods made with fish that are lower in mercury, such as salmon. Our guide on how to choose healthy cat food can help.

When should you call the vet?

Call your vet if a cat that eats a lot of tuna shows loss of coordination or balance, or has difficulty walking. These can be signs of mercury poisoning, and they can also look like thiamine deficiency. Both need a vet’s attention.