---
title: "Can Cats Eat Tuna UK?"
description: "UK guide — occasional plain tinned tuna in spring water is usually safe. Daily tuna risks mercury, nutrient imbalance, and addiction."
url: "https://pethealth.org.uk/health/can-cats-eat-tuna-uk"
canonical: "https://pethealth.org.uk/health/can-cats-eat-tuna-uk"
date_published: "2026-06-25"
date_modified: "2026-06-25"
source: "PETHEALTH+"
---

# Can Cats Eat Tuna UK?

**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.

## 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](/health/kidney-disease-in-cats) — dietary restrictions may apply

## Related guides

- [Cat food safety hub](/cat-food-safety)
- [Can cats eat ice cubes UK](/health/can-cats-eat-ice-cubes-uk)
- [Kidney disease in cats](/health/kidney-disease-in-cats)

## FAQs

### 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.

## Sources

- [PDSA — Cat diet](https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub)
- [Blue Cross — Feeding your cat](https://www.bluecross.org.uk/pet-advice)
- [Cats Protection — Cat care](https://www.cats.org.uk/help-and-advice)

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Last modified: 2026-06-25