Cats have a reputation for being fiends for fish. How many cartoons and children’s books are there depicting cats proudly lounging around on piles of fish bones?
But is fish bad for cats?
Fish has a lot of nutrients, right? It’s full of healthy fats and lean protein. Everyone should be eating more fish, according to nutritionists! There are a few really good reasons you should think carefully about how much fish you give your cat, and even what kind of fish you choose.
Cats and Fish: A Short History
When you think about it, most ancient cats weren’t eating fish. Domestic cats evolved from desert-dwelling felines which almost certainly subsisted on birds and lizards, not fish. So from an evolutionary standpoint, it’s not like cats have a “need” for fish. But ancient cats also didn’t use litter boxes, so really, history’s not a good enough reason to keep your cat away from something. Why else should fish be suspect?
Histamines, Toxins, and Heavy Metals (Oh My!)
Fish has a lot of histamines. What are histamines? They’re compounds released by white blood cells to ward off inflammation, which is good, but they’re also responsible for some of the most annoying allergy symptoms. Everyone reacts differently to histamines, including cats, so eating histamine-rich fish can potentially cause an allergic reaction to occur...in fact, fish is considered by vets to be one of the most allergy-inducing food sources around. And what about toxins? Think about it: Fish swim in polluted rivers and oceans, and a lot of evidence suggests they might (might!) be picking up serious toxins while they’re at it. PCBs and pesticides are two big concerns, not just for cats but humans, too. Lastly, consider that many species of fish have a serious problem with heavy metal contamination. Some fish like shark and swordfish are so reliably contaminated with metals like mercury and magnesium that human doctors actually advise women of childbearing age not to eat them. If you wouldn’t feed it to yourself, you probably shouldn’t feed it to your cat.
Fish as Part of a Balanced Cat Diet
All that scary stuff to say...fish can be a part of a balanced diet for cats! The trick is moderation, of course, and also choosing the right way to serve fish. Lots of canned cat foods come in “fish” flavors, but they’re usually comprised of a hodgepodge of fish and fish by-products like bones and scales. If you’re going to feed your cat canned fist, stick to single-ingredient stuff (sustainably farmed where possible!) and don’t do so every night. Avoid fish like Tilefish and Tuna as they tend to be some of the most heavily contaminated. It’s not a bad idea to feed your cat real, skin-on fish when you want to give her a briny treat. Just choose fish you would eat yourself, and be sure there are no bones. Fish does have a lot of heart-healthy Omega-3 and Omega-6 fatty acids, so including it as part of a balanced diet can help your cat stay on the right track. Never feed your cat raw fish as it can contain harmful pathogens. And one more thing about fish...don’t go overboard! (Sorry.) Cats who primarily eat fish are actually at a high risk for thiamine deficiency, thiamine being a necessary vitamin that’s added to most commercial cat foods. Stick to fish as an occasional treat and your cat will be fine - and maybe even grateful, if you’re lucky!