Can Cats Eat Tuna?

If you've ever opened a can of tuna near a cat, you already know the reaction. They come running from three rooms away, meowing, weaving between your legs, completely single-minded about getting to that fish. It's one of the most relatable things about cats — and one of the things that leads a lot of well-meaning owners to use tuna as a regular treat or food supplement.

The problem is that tuna, while not toxic to cats, comes with a set of risks that make it a poor choice for anything more than occasional use. Understanding those risks can help you make a smarter call about how and when to share tuna with your cat.

Why Cats Love Tuna So Much

Cats are obligate carnivores, meaning they're biologically wired to be attracted to meat and fish. Tuna has an extremely strong smell and flavor profile that activates cats' hunting instincts at a deep level. Some researchers believe cats may also be drawn to tuna's high levels of free amino acids, which signal high protein content.

Here's the thing though: just because cats love something doesn't mean it's good for them. Cats are famously bad judges of what's nutritionally appropriate — they'll eat spoiled food, obsess over one ingredient while ignoring others, and develop dietary preferences that can actually harm them over time. Tuna is one of those cases where instinct and health don't perfectly align.

The Real Risks of Feeding Tuna to Cats

1. Mercury Poisoning

Tuna — particularly larger species like albacore and bluefin — sits high in the ocean food chain and accumulates mercury through a process called biomagnification. Fish lower in the chain absorb mercury from their environment; larger fish eat those fish and absorb even more. By the time tuna reaches your plate (or your cat's bowl), it carries significantly higher mercury levels than smaller fish like sardines or anchovies.

Mercury poisoning in cats is not an immediate crisis from a single meal, but it accumulates over time. Cats fed tuna regularly can develop what vets describe as "staggering disease" — a form of mercury toxicity that causes loss of coordination, difficulty walking, and neurological symptoms. It's chronic, insidious, and largely preventable.

2. Thiamine Deficiency

Raw tuna contains an enzyme called thiaminase, which destroys thiamine (vitamin B1) — a nutrient that's critical for cats' neurological function. Canned or cooked tuna has much lower thiaminase activity, but if tuna becomes a significant part of a cat's diet, thiamine deficiency can still develop. Symptoms include dilated pupils, loss of balance, seizures, and in severe untreated cases, death.

3. Nutritional Imbalance

Tuna is not nutritionally complete for cats. It lacks several essential nutrients including adequate vitamin E, and its high phosphorus content can be problematic for cats with kidney disease. A cat that fills up on tuna may eat less of its complete, balanced cat food — gradually developing deficiencies that don't become visible until they're causing real damage.

4. Tuna Addiction

This sounds like a joke but veterinary nutritionists take it seriously. Some cats become so fixated on tuna that they refuse to eat anything else — including their regular cat food. This creates a cycle where owners feed more tuna to get the cat to eat, which deepens the preference, which makes the cat even less interested in anything else. Breaking a tuna addiction can take weeks of patient transition feeding.

What Type of Tuna Is Safer?

How Much Tuna Can Cats Have?

Most veterinary nutritionists suggest that treats of any kind — including tuna — should make up no more than 10% of a cat's total daily caloric intake. For a typical adult cat eating around 200-250 calories per day, that's roughly a teaspoon to a tablespoon of tuna.

Frequency-wise, once or twice a week at most is a reasonable limit. If you're using it as a training reward or occasional treat, small amounts are fine. Where things go wrong is when tuna becomes a daily meal or a food topper applied to every serving.

Frequently Asked Questions