Can cats eat tuna?

The short answer is: yes, occasionally — but tuna should never be the main component of a cat's diet.

Why cats love tuna

Tuna has a strong smell and high protein content that cats find irresistible. A small piece of plain, cooked tuna (or a treat that lists tuna as an ingredient) once or twice a week will not harm a healthy adult cat.

The risks of too much tuna

- Mercury toxicity – Tuna accumulates mercury from the ocean. Cats fed tuna daily can build up dangerous mercury levels, potentially causing neurological damage over time.
- Nutritional deficiency – Tuna alone does not provide the complete nutrition cats need. Critically, it lacks sufficient taurine — an amino acid cats cannot produce on their own and must obtain from food. Taurine deficiency causes dilated cardiomyopathy (a serious heart condition) and can lead to blindness.
- Thiamine (Vitamin B1) deficiency – Raw tuna contains an enzyme (thiaminase) that breaks down thiamine. A thiamine-deficient cat develops neurological signs including seizures. Cooking destroys this enzyme, but canned tuna in brine or oil can still be problematic if fed in large amounts.
- Addiction – Cats can become strongly attached to the intense flavour of tuna and begin refusing a balanced diet. This creates a nutritional problem that can be difficult to reverse.

Safer alternatives

Choose a commercially complete cat food with fish as an ingredient — these are formulated to be nutritionally balanced. If you want to give treats, small pieces of cooked salmon or whitefish are lower in mercury than tuna.