Can cats eat Raw tuna / raw fish?
Caution. Raw fish (including sushi-grade tuna, salmon, and mackerel) carries parasitic risk, thiaminase (which destroys thiamine), and the same mercury concerns as cooked tuna in larger amounts.
Key facts
- Verdict: Caution — some risk involved. See the detail below before giving raw tuna / raw fish to your cat.
- Category: Fish
- Onset: Signs can start hours after a large raw feed — see the full timeline below.
If your cat has eaten raw tuna / raw fish
- For a small amount of raw fish: monitor.
- For larger amounts or cats fed raw fish regularly: discuss with your vet.
What's the full picture?
Raw fish contains thiaminase, an enzyme that breaks down thiamine (vitamin B1) before the cat's body can use it. This isn't an issue from a single taste, but a cat fed raw fish regularly — as a base ingredient in a homemade raw diet, for example — can develop a genuine thiamine deficiency over weeks, since the enzyme keeps destroying thiamine faster than the cat can absorb what it needs. Thiamine is essential for normal nervous system function, so a deficiency causes neurological signs that get progressively worse the longer the deficient diet continues, and can be fatal if not corrected.
Parasites are the other main concern with raw fish bought for human consumption, including sushi-grade tuna and salmon. Even fish sold as 'sushi grade' in UK supermarkets has typically been flash-frozen to kill parasites for human food safety purposes, but this doesn't eliminate every bacterial risk, and home handling and storage can reintroduce contamination. Tapeworms and roundworms picked up from raw fish are treatable with standard deworming medication but are an avoidable hassle and health burden for the cat in the meantime.
A realistic UK household scenario is a cat snatching a piece of raw salmon or tuna during meal prep, or being given a taste of sashimi left over from a takeaway. A one-off small taste like this isn't a crisis — it's very unlikely to cause thiamine deficiency from a single exposure, and the parasite risk from a single piece is low, though not zero. The real risk builds with repetition: cats fed raw fish as a regular component of their diet, whether through a homemade raw food plan or frequent treats, are the ones who actually develop problems.
Cooking eliminates both concerns almost entirely, since heat destroys thiaminase and kills parasites and most relevant bacteria — which is why cooked fish is treated very differently on this site. If you want to feed fish as a raw diet component, do it under veterinary or veterinary-nutritionist guidance so thiamine and other nutrients are properly balanced, rather than relying on raw fish alone.
Symptoms to watch for
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Questions owners ask
My cat stole a piece of raw salmon — should I panic?
No, a single small taste of raw fish is very unlikely to cause thiamine deficiency or a parasite problem. Just watch for any digestive upset over the next day and don't make it a regular habit.
Is sushi-grade tuna safer than regular raw fish?
It's generally frozen to reduce parasite risk for human consumption, which helps, but it doesn't remove the thiaminase issue with regular feeding, and freezing doesn't guarantee zero bacterial risk once it's been out and handled.
Can I feed my cat a raw diet based on fish?
Not as the main or sole protein source without expert guidance. Regular raw fish feeding is exactly the scenario that causes thiamine deficiency, so a fish-based raw diet needs to be balanced with a thiamine supplement and planned with a vet or veterinary nutritionist.
How is thiamine deficiency treated if it's caught?
Vets treat it with thiamine injections or supplementation alongside switching the diet away from raw fish. Caught early, most cats recover well; the concern is mainly with cases that go unnoticed until neurological signs are advanced.
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Related
Sources referenced for this guidance
- Veterinary Poisons Information Service (VPIS) — UK clinical toxicology reference used by vets
- International Cat Care — feline-specific clinical guidance
- BSAVA — British Small Animal Veterinary Association reference materials
- Merck Veterinary Manual — professional veterinary reference
About this guidance
Every entry on this site is compiled from published UK veterinary toxicology sources — International Cat Care, Veterinary Poisons Information Service (VPIS) references, RCVS-registered practice materials, and peer-reviewed feline medicine literature. Where the evidence is mixed, we err on the cautious side because cats are unusually sensitive to many common substances that are harmless to humans and even to dogs.
This is general information written for UK cat owners. It is not personalised veterinary advice for your specific cat, their age, weight, medical history, or the exact exposure you're dealing with. If your cat has eaten something or is unwell, call your vet first. The Animal PoisonLine on 01202 509000 is available 24/7 for a small fee and can tell you whether an emergency visit is needed.
Entries are reviewed and updated as new research emerges. Spotted an error? Let us know — corrections are investigated and applied within 24 hours. For more context on how we work, see about and our full disclaimer.
Last reviewed: · By the What Can My Cat Eat? editorial team