Tuna: the fish that drives every cat wild
Open a can of tuna. In 5 seconds, your cat is in front of you. Even if they’ve never heard it before. It’s one of the strongest "lures" in the feline world.
But is tuna really that harmless? Online, you'll find opposing views:
- "Never give tuna: it’s disguised poison."
- "My cat has been eating tuna for years, they’re doing great."
Let's take a look at the balanced scientific view.
Why cats love tuna
Tuna contains:
- High concentration of free glutamate (the "umami" flavor).
- Intense aroma (volatile compounds).
- Fats that activate pleasure centers.
For the carnivorous cat, it’s a super-stimulus for food.
Fun fact: cats cannot perceive sweet flavors (they lack the receptor), but they are hypersensitive to umami. Tuna is "pure umami."
The benefits of tuna
1. High palatability
Useful for:
- Ill cats that aren’t eating.
- Post-operative recovery.
- Stimulating appetite.
2. Quality protein
Typical composition (100g tuna in water):
- 22-26 g protein.
- 1-2 g fat (variable).
- B vitamins.
- Minerals.
3. Omega-3
Especially fresh tuna.
Benefits: coat, joints, heart.
4. Versatility
- As a treat.
- To stimulate new food (mixed).
- To administer medications.
The risks of tuna
Risk 1: mercury
Truth: tuna is a high-level predator in the food chain. It bioaccumulates mercury absorbed from smaller fish.
Types of tuna and mercury levels:
- Albacore tuna (white): high mercury.
- Yellowfin tuna: medium.
- Skipjack tuna: low (smaller).
- Commercial canned tuna: variable.
Consequences for cats:
- Chronic mercury poisoning (rare but possible).
- Long-term neurological problems.
- Renal toxicity.
Real risk: a cat that eats tuna daily for years = possible problem.
Cat that eats tuna occasionally: negligible risk.
Risk 2: vitamin E deficiency
Tuna is low in vitamin E but high in unsaturated fats.
Consequence of a tuna-heavy diet:
- Scelerosing lipogranuloma (inflammation of body fat).
- Pain, fever, sensitive skin.
- Curable, but avoidable.
Risk 3: thiamine
Raw tuna contains thiaminase: an enzyme that destroys vitamin B1 (thiamine).
Consequences:
- B1 deficiency.
- Neurological problems.
Cooked tuna: no problem (thiaminase destroyed by heat).
Sushi/sashimi: dangerous in the long term.
Risk 4: food dependence
Some cats become "tuna addicts":
- Refusing other foods.
- Wanting only tuna.
Problem: poor, unbalanced diet.
Risk 5: salt
Canned tuna in brine has a high salt content.
Consequences:
- Dehydration.
- Kidney overload.
- Dangerous for cats with renal/cardiac issues.
Solution: only tuna in water, never in brine.
Risk 6: wrong oils
Oil-packed tuna:
- Excess oil = gastric problems.
- Sometimes low-quality oils.
Solution: only tuna in water.
Risk 7: added ingredients
Commercial tuna can contain:
- Preservatives.
- Flavors.
- Salt.
- Acids.
Solution: read the label. Only tuna + water.
The scientific position
Veterinary nutritionists agree:
- ✅ Occasional tuna (1-2 times a month): safe for healthy cats.
- ✅ Tuna as a "treat" (a teaspoon a day): safe.
- ❌ Tuna as the main or daily meal: multiple risks.
- ❌ Tuna in brine, oil-packed, with salt: never.
- ❌ Regular raw tuna: thiamine risk.
What to look for in tuna
If buying for your cat
What:
- Natural tuna (in water).
- No added salt (in water, no brine).
- No preservatives.
- Optionally cat-specific (premium brands).
Specific brands for cats:
- Almo Nature only tuna.
- Schesir natural tuna.
- Cosma Tuna.
Pros:
- Balanced.
- Specific to feline needs.
- No dangerous ingredients.
Cost: €1.50-3.50 per can.
Tuna for humans (occasional)
If using tuna for humans:
- Only "natural" / "in water".
- Rinse before serving.
- Small portion (1-2 teaspoons).
- Never daily.
The quantities
Average cat (4 kg):
Tuna as an occasional treat:
- 1-2 teaspoons.
- 1-2 times a week max.
Tuna to stimulate appetite (post-illness):
- 1-2 teaspoons per meal.
- Under veterinary advice.
Tuna mixed with regular food:
- 1 teaspoon as a "topping".
- For picky eaters.
Never:
- Tuna as a regular substitute meal.
- More than 30 g total per week.
Alternatives to tuna
If you want to stimulate appetite without the risks of tuna:
- Boiled salmon:
- Better nutritional profile.
- High omega-3.
- Less mercury.
- Boiled chicken:
- Top for palatability.
- Safe, neutral.
- Boiled chicken heart:
- Beloved by cats.
- High-quality protein.
- Sardines in water:
- Small fish = less mercury.
- High omega-3.
- Safe in small quantities.
- Specific cat snacks:
- Various brands of "cat tuna".
- Balanced.
Cats that SHOULD NOT eat tuna
- ❌ Cats with kidney issues: salt and phosphorus.
- ❌ Cats with heart problems: sodium.
- ❌ Cats with fish allergies: obviously.
- ❌ Epileptic cats: some studies suggest caution.
- ❌ Kittens under 6 months: diet must be balanced.
The personal experiment
To test whether your cat reacts well:
- First time: 1 teaspoon of tuna in water.
- Observe for 24-48 hours:
- Diarrhea?
- Vomiting?
- Irritated skin?
- If okay: occasional.
- If symptoms: never again.
Tuna for sick cats
Specific veterinary indication:
Cats that aren't eating anything (risk of hepatic lipidosis):
- Tuna to stimulate appetite.
- Even a teaspoon can "break" the fast.
- Under veterinary control.
Life of a cat > occasional mercury risk.
The common story
Real case:
14-year-old cat, ate human tuna daily for 10 years (in brine).
Problems:
- Overweight.
- Early kidney failure.
- Chronic dehydration.
Contributing cause: tuna-based diet.
Lesson: daily tuna = problems.
The truth
Tuna is NOT "poison":
- Safe occasionally.
- Dangerous regularly.
Golden rules:
- ✅ Only natural (in water, no salt).
- ✅ Only occasionally (1-2 times a week max).
- ✅ Only as a treat, never a main meal.
- ✅ Cooked, never raw.
- ❌ Never human tuna in brine.
- ❌ Never a tuna-based diet.
- ❌ Never cats with kidney problems.
Your cat can enjoy tuna for years without problems if you follow the rules.
And remember: their wide-open eyes in front of the can are adorable. But their long-term well-being comes before the moment's pleasure.
Tuna = yes, in moderation.
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