Cat Health
Can Cats Eat Tuna UK?
By Kaiser Khan, EditorPublished Last updated 2 min read
Quick answer
Occasional plain tinned tuna in spring water is usually fine as a treat. Do not feed tuna daily — it is not nutritionally complete, can cause mercury build-up over time, and some cats become fixated and refuse proper cat food.
Key takeaways
- Occasional plain tinned tuna in spring water (not brine or oil) is usually safe as a treat. Tuna should not replace complete cat food — daily feeding causes nutritional problems.
- No — daily tuna lacks essential nutrients cats need and can cause mercury accumulation and 'tuna addiction' where cats refuse balanced food.
- Kittens need complete kitten food for growth. Plain tuna alone does not provide balanced nutrition — ask your vet before offering any human food to kittens.
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Can cats eat tinned tuna?
According to the PDSA and Blue Cross, a small amount of plain tinned tuna in spring water — drained, with no added salt — can be an occasional treat for most healthy adult cats.
Tuna is not a balanced meal. Complete wet or dry cat food provides taurine, vitamins, and minerals that tuna alone lacks.
Tuna in brine or oil — avoid
| Product | Problem |
|---|---|
| Tuna in brine | High salt — harmful to cats |
| Tuna in sunflower or olive oil | Excess fat — digestive upset |
| Flavoured tuna | Onion, garlic, spices — toxic |
| Human tuna sandwiches | Mayonnaise, onion, bread — unsuitable |
Why daily tuna is a problem
Nutritional imbalance
Cats need taurine, calcium, and balanced vitamins from complete cat food. Feeding mostly tuna can contribute to serious deficiency over time.
Mercury
Large predatory fish accumulate mercury. Occasional small amounts are unlikely to harm healthy cats; regular daily feeding increases long-term risk — especially in kittens and pregnant queens.
Tuna addiction
Some cats develop a strong preference for tuna and refuse their normal diet. This makes balanced feeding difficult and can lead to weight loss or deficiency.
Fresh tuna
Plain cooked fresh tuna without seasoning can be offered in small amounts — same rules as tinned: occasional only, not a staple.
Never feed raw fish regularly without veterinary nutrition advice — thiaminase in some raw fish can affect vitamin B1 if fed in large amounts over time.
When to see your vet
Book a check if your cat:
- Refuses all cat food and only wants tuna
- Loses weight while eating human food
- Vomits or has diarrhoea after tuna
- Is a kitten, pregnant, or has kidney disease — dietary restrictions may apply
Related guides
Sources & further reading
This guide draws on the publicly available UK advice listed below. Follow the links for the relevant guidance or the organisation's broader care resources.
PETHEALTH+ is independent. These organisations do not sponsor, approve, or partner with this website. Editorial sources and further reading (last updated 2026-06-25).
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Also see symptoms, symptom checker, and poison guide.
Frequently Asked Questions
- Can cats eat tuna?
- Occasional plain tinned tuna in spring water (not brine or oil) is usually safe as a treat. Tuna should not replace complete cat food — daily feeding causes nutritional problems.
- Can cats eat tinned tuna every day?
- No — daily tuna lacks essential nutrients cats need and can cause mercury accumulation and 'tuna addiction' where cats refuse balanced food.
- Can kittens eat tuna?
- Kittens need complete kitten food for growth. Plain tuna alone does not provide balanced nutrition — ask your vet before offering any human food to kittens.
- Is tuna in brine or oil safe for cats?
- Avoid brine (high salt) and oil (high fat). Choose plain tuna in spring water with no added salt — drain well and offer small amounts only.