The short answer: It is not recommended.
The long answer: Having longer life spans than other fish, tuna contains high levels of mercury, metals, and unsaturated fats. As such, it is not recommended for cats to consume tuna on a regular basis. Too much mercury may lead to mercury poisoning, and may cause your cat to lose her balance, have a difficult time walking, and become uncoordinated.
Canned tuna may be given to cats sparingly as long as they are prepared properly. Choose the ones packed in fresh water instead of those in brine or oil. Also, check the label for toxic ingredients such as salt. Too much salt can cause vomiting, lethargy, incoordination, diarrhea, decreased appetite, and/or excessive thirst or urination in your cat. In some extreme cases, it may even cause tremors, seizures, or coma. Oil, on the other hand, may lead to digestive upset.
According to The Spruce Pets, the best canned tuna option is chunk-light tuna since albacore contains higher levels of mercury.
What to do if your cat accidentally eats canned tuna: Check the ingredients of the canned tuna, and note how much your cat has eaten. If your cat displays unusual symptoms over the next 24 hours, contact your veterinarian immediately.
Symptoms of cat poisoning are salivation, vomiting, diarrhea, twitching and fitting, difficulty in breathing, shock, and collapse. Inflammation or swelling of the skin, depression, coma, and changes in drinking, urinating, and appetite may also occur.
In summary: High in protein and omega-3 essential fatty acids EPA and DHA, tuna may help improve your cat’s skin, coat, and inflammatory conditions. However, it is not recommended for cats to eat canned tuna since it may contain harmful ingredients.