You've probably seen or heard countless stories of cats loving fish, but as far as cats eating tuna goes, is it really a good idea? And can cats eat tuna that's made for human consumption?

Here's why you may want to reconsider sharing your favorite canned tuna with your feline friend.

Can Cats Eat Tuna?

The simple answer is that cats are attracted to tuna. They love the powerful smell and the robust flavor of this fish, and a spoonful of tuna has been known to make the medicine go down easily.

However, though not on the list of toxic foods for cats, tuna that's meant for people can cause health issues for cats. While a single bite may not do any harm, it's best to take tuna out of their bowl entirely.

How Tuna Can Affect Cat Nutrition

well-balanced meal plan for cats includes protein, essential fatty acids, vitamins, minerals, and other nutrients. When your kitty eats too little or too much of certain nutrients, health complications can arise.

Tuna on its own is not nutritionally balanced. For example, tuna has too much unsaturated fat and is not supplemented with Vitamin E or other antioxidants. Therefore, tuna should not be fed as your cat's primary source of nutrition.

If tuna is part of your cat's meal plan and you notice them acting out of sorts, consider taking them into your veterinarian for a wellness visit — it's always a good idea to get a baseline reading to ensure nothing serious is going on.

Why Cats Eating Tuna May Gain Weight

Most indoor cats aren't very active and don't require a lot of calories — meaning weight gain can easily creep up. According to recommendations set forth by the World Small Animal Veterinary Association, a cat that weighs 11 pounds should consume 290 calories per day.

When human foods are converted to kitty calories, it is easy to see that foods intended for humans have far too many calories for our feline companions. A few ounces of canned tuna in water contains almost 100 calories, which is more than a third of the recommended daily caloric intake for many cats.

Not All Cats Can Stomach Tuna

Cats can also be allergic to fish. The Merck Veterinary Manual lists fish as a top food allergen for cats, noting that common signs of an allergic reaction include itching, hair loss, red or swollen skin and red bumps. Cats with food allergies may also vomit and experience diarrhea, gas and a loss of appetite if they encounter an ingredient they're sensitive to. If you notice any of these symptoms, call your veterinarian right away to determine the causes and create a treatment plan.

Tuna Is High in Mercury

Tuna is high in mercury, a toxic metal. Frequent consumption of tuna may also lead to mercury poisoning explains Cailin Heinze, a veterinary nutritionist at the Cummings School of Veterinary Medicine at Tufts University. Symptoms of mercury poisoning include dizziness and loss of coordination and balance. Pet parents should keep albacore tuna, in particular, away from cats because it "is from a larger species of tuna with mercury levels almost three times higher (than chunk-light)," says Heinze.

So, can cats eat tuna? Tuna is not nutritionally balanced and should not be fed as a large part of your cat's meal plan. Even giving canned tuna as a treat can lead to health issues, especially if it is given in large amounts or frequently. To ensure your feline friend is getting the balanced nutrition they need without extra calories or toxic metals, choose a healthy cat food that uses tuna in a way that still meets their nutritional needs and satisfies their taste buds. Visit a Veterinarian for more information regarding what nutrition is adequate for your pet.

Christine O'Brien Christine O'Brien

Christine O'Brien is a writer, mom, and long-time cat parent whose two Russian Blues rule the house. Her work also appears in Care.com, What to Expect, and Fit Pregnancy, where she writes about pets, pregnancy, and family life. Find and follow her on Instagram and Twitter @brovelliobrien.