Can Cats Drink Tuna Water?

What makes tuna water so appealing to cats, and is it actually safe? Your cat goes crazy when you open a can of tuna, and you're wondering if the leftover juice is a safe treat. The answer is complicated. Tuna water can be okay in tiny amounts—but most canned tuna comes packed in way too much salt. Cats love the smell and taste of tuna water, which makes it tempting to use. But what your cat wants and what's good for them aren't always the same thing.

Tuna water is not toxic, but it's not particularly safe either. The problem is salt. Most canned tuna—even the stuff marketed as 'in water'—has added sodium. Cats need very little sodium in their diet, and their kidneys aren't built to handle large amounts. A teaspoon of salty tuna water once in a while probably won't cause problems. But daily tuna water, or large amounts, can lead to dehydration, kidney issues, and sodium toxicity. Even if you find low-sodium tuna, there's another issue: mercury. Tuna accumulates mercury, and that includes the water it's packed in.

The appeal is obvious—cats go absolutely nuts for tuna. Opening a can of tuna is like ringing the dinner bell. Some owners pour a little tuna water over dry food to make it more appealing. Others use it to encourage a sick cat to drink. And honestly, it works. The smell is irresistible to most cats. But just because it works doesn't mean it's safe to use regularly. Think of tuna water like candy for kids—effective motivation, but not something you want to rely on daily.

Not all tuna water is equally risky. What the tuna is packed in makes a huge difference.

Cats love tuna water, but their bodies don't. The salt content is the first problem. Cats evolved to get moisture from prey, which has very low sodium. Their kidneys are efficient at conserving water, but they're not designed to filter out excess salt. Too much sodium forces their kidneys to work harder, which can lead to chronic kidney disease over time—and kidney disease is already one of the most common health problems in older cats. The second problem is mercury. Tuna is a large, long-lived fish that accumulates mercury. Cats fed tuna or tuna water regularly can develop mercury poisoning, which affects the nervous system.

The risks increase with frequency and amount.

This is where tuna water might actually be useful—but only in very specific situations. If your cat is refusing to drink plain water and you're worried about dehydration, a tiny bit of diluted, low-sodium tuna water might encourage them to lap up some liquid. This is a short-term bridge to get your cat to the vet, not a solution. And it only works if the tuna water is truly low-sodium. Regular tuna water with added salt will make dehydration worse, not better.

There are safer ways to make water appealing to your cat. Low-sodium bone broth made specifically for cats has flavor without the mercury or excessive salt. Cat water fountains encourage drinking because moving water attracts cats. Wet cat food provides hydration along with proper nutrition. If you want to add flavor to water occasionally, try freezing small amounts of low-sodium chicken broth into ice cubes—your cat can lick them, and the flavor disperses slowly without overwhelming their system with salt.

No. Kittens are more sensitive to sodium and mercury than adult cats. Their developing kidneys can't handle excess salt, and their smaller bodies accumulate mercury faster.

If your cat had a small amount from a low-sodium can, they're probably fine. But watch for symptoms.

Absolutely not. Daily tuna water is a recipe for kidney problems and mercury toxicity. Even low-sodium tuna water shouldn't be a daily drink. Mercury accumulates in the body over time—it doesn't get flushed out quickly. Regular exposure, even in small amounts, can lead to mercury poisoning. Symptoms include loss of coordination, tremors, and behavioral changes. Daily sodium exposure, even from 'low-sodium' sources, puts stress on the kidneys. If your cat loves tuna water so much you're tempted to give it daily, that's a sign you should stop completely and let their taste preferences reset.

Yes. Tuna accumulates mercury from the ocean, and that mercury is present in the water the tuna is packed in. The amount varies depending on the type of tuna—albacore (white tuna) has more mercury than light tuna—but all tuna contains some. For humans, moderate tuna consumption is considered safe. For cats, who are much smaller and more sensitive, the mercury risk is higher. This is why tuna and tuna water should be occasional treats, not regular foods.

You can, but only as a last resort and only short-term. If your cat is refusing water and you're worried about dehydration, a tiny amount of heavily diluted, no-salt-added tuna water might work as a bridge to get them drinking. But this should be a one-time or very occasional strategy, not a regular practice. If you find yourself needing to flavor your cat's water regularly to get them to drink, that's a medical issue that needs a vet, not a tuna can. Chronic low water intake can indicate kidney disease, diabetes, or other serious problems.