Why you shouldn't be feeding your cats canned tuna
When you think about what cats might like to eat, one of the first things that usually comes to mind is tuna. We often see cats being fed out of tuna cans in movies, so it would make sense for a first-time owner to think it's OK to do the same.
However, while it may look and smell a bit like cat food, canned tuna fish that's prepared for humans is not something you should be feeding your feline friend on the regular. First and foremost, if you only feed them tuna, you'll be denying them the other necessary nutrients their bodies need to stay healthy. While it is serious protein, it alone is not enough to keep them from becoming malnourished.
Yes, you'll find a lot of cat foods, especially wet cat foods, have tuna in them because, well, cats go crazy for tuna. However, you'll also notice there are other things in there besides tuna, whereas tuna for human consumption is often just tuna or tuna soaked in oil, which increases the fat content exponentially.
Speaking of fats, tuna is exceptionally high in unsaturated fats, which while good for humans, is not so much for cats. According to pet blogger Abby Rosenberg, having too much unsaturated fat in a cat's diet can cause a vitamin E deficiency, leading to inflammation of the fatty tissue, a condition known as steatitis.
Tuna also has a high mercury count, just like salmon and similar upper food-chain fish. Pregnant women are often discouraged from eating tuna for this reason. Since your cat is much smaller than a human, eating too much of it over even a short period of time can give it mercury poisoning.
Then there's the tuna junky factor. Tuna in general has a strong, pungent odor that cats just love, and in some cases have a hard time doing without. I remember when I started feeding my own cats a grain-free cat food that had a bit of tuna in most of its canned meals, my cats became crazy addicts. They started bullying my fiancé and me to feed them breakfast earlier and earlier in the morning so they could get their fix. I tried switching them to a different brand that utilized more chicken and beef, but they would have none of it. Let's just say rehabilitation took a lot of extra treats.
That being said, tuna in moderation is actually good for your pet, and excluding it all together could be denying them a great source of protein. However, if you're going to feed them tuna, try to get it from a well-reputed cat food brand. If you choose to feed them human-grade tuna from a can, do so sparingly and only as a special treat.