Can Cats Eat Tuna?

At 28g of protein per 100g, tuna is one of the most protein-dense foods available. For obligate carnivores who need 30-45% protein in their diet, the amino acid profile of tuna is biologically appropriate and highly digestible. The protein quality is excellent, providing all essential amino acids cats require.

Tuna's intense aroma can break through appetite suppression in sick, post-surgical, or elderly cats who refuse to eat. A tablespoon of tuna or tuna juice on top of regular food can be the difference between a cat eating and not eating. When a cat hasn't eaten in 48+ hours (risking hepatic lipidosis — fatty liver disease), tuna's palatability can be genuinely lifesaving.

While lower in omega-3s than salmon, tuna still provides EPA and DHA — anti-inflammatory fatty acids that support skin, coat, brain, and joint health. Fresh tuna has more omega-3s than canned; canned in water retains more than canned in oil. For cats who can't eat salmon, tuna is an alternative omega-3 source.

Canned tuna in water has only 1.3g of fat per 100g, making it one of the leanest protein sources available. For overweight cats who need high-protein, low-fat treats, small amounts of water-packed tuna can be appropriate — if used infrequently enough to avoid mercury and addiction issues.

Tuna is a large, long-lived predatory fish that bioaccumulates mercury throughout its life. Average mercury content is 0.35 ppm — significantly higher than salmon (0.02 ppm) or shrimp (0.01 ppm). Cats weigh just 2-8 kg, so their safe mercury threshold is extremely low. Chronic mercury exposure causes neurological damage, kidney damage, and behavioral changes. Larger tuna species (bigeye, albacore) have even higher mercury levels than skipjack or light tuna.

"Tuna addiction" is a recognized phenomenon in veterinary practice. Some cats become so fixated on tuna that they refuse their nutritionally complete cat food entirely. This leads to nutritional deficiencies because tuna alone lacks adequate vitamin E, calcium, thiamine, and other essential nutrients. Breaking a tuna addiction requires patience — gradually reducing tuna while mixing it with regular food over weeks.

Despite its high protein, tuna is deficient in several nutrients cats need: vitamin E (deficiency causes steatitis/yellow fat disease), calcium (deficiency causes bone weakness), copper, and adequate taurine levels. Cats fed exclusively tuna for extended periods develop steatitis — a painful inflammatory condition of the fat tissue, also called "fish disease." Tuna is a treat, never a diet.

Most canned tuna intended for human consumption contains significant added sodium — often 200-400mg per serving. This level of sodium is excessive for a small cat and can contribute to dehydration, elevated blood pressure, and kidney strain. If offering canned tuna, choose low-sodium or no-salt-added varieties, and drain thoroughly.

Tuna that hasn't been properly refrigerated can develop high histamine levels (scombroid), causing allergic-type reactions: vomiting, diarrhea, swelling, and difficulty breathing. Cats are susceptible to histamine reactions from fish. Only use fresh tuna that has been properly stored or reputable canned tuna brands.

Use canned chunk light tuna (skipjack) in water — lowest mercury option among canned varieties

Drain the tuna thoroughly to reduce sodium content

If using fresh tuna, cook completely — no seared or raw preparations (raw fish carries parasites and thiaminase)

Flake into small pieces and serve a measured portion — resist the urge to give more when your cat begs

Never serve tuna in oil — the added fat is unnecessary and can cause pancreatitis

Tuna water appetite stimulant

Instead of giving solid tuna, drizzle a teaspoon of the water from a can of tuna (no-salt-added) over your cat's regular food. This provides the irresistible tuna scent without the mercury load of eating the actual fish. It's the safest way to use tuna's palatability advantage.

Emergency appetite rescue

When a cat hasn't eaten for 24+ hours (which risks hepatic lipidosis in cats — a potentially fatal liver condition), a small amount of tuna on top of regular food can restart eating. In this context, the mercury concern is outweighed by the immediate danger of anorexia. Consult your vet if food refusal persists beyond 48 hours.

Medication concealer (occasional use only)

A small amount of mashed tuna can disguise pills for cats who refuse all other food vehicles. The powerful scent overwhelms medication odors. Use this method sparingly — you don't want to create a tuna association that leads to fixation. Rotate with other foods like chicken or egg.

Diluted in water for hydration

Add 1 teaspoon of tuna water to your cat's drinking water to encourage fluid intake. Replace daily to prevent bacterial growth. This can be especially helpful for cats with kidney disease who need increased hydration but refuse plain water. Consult your vet about sodium intake if your cat has kidney issues.

These breeds are known for becoming intensely fixated on preferred foods — tuna addiction is a particular risk. If you offer tuna to a Siamese, be prepared for dramatic vocal demands for more. It's often easier to never start feeding tuna to these breeds than to manage the resulting food obsession.

Large breeds with higher caloric needs might seem like they can handle more tuna, but mercury accumulation is dose-dependent — more tuna means more mercury regardless of body size. Stick to the maximum once-per-week frequency. These breeds' predisposition to HCM makes nutritional balance especially important.

Older cats with kidney disease — extremely common in aging felines — should have tuna limited or avoided entirely. Mercury is processed through the kidneys, and compromised kidneys handle toxins less efficiently. The high sodium in most canned tuna further stresses aging kidneys. Consult your vet before offering tuna to senior cats.