Should fish be a part of a cat diet?

We all know fish is a good food to add to our diet; in fact, nutritionists advise that everyone should be eating more fish. But one question a lot of cat owners are asking is, “should fish be a part of a cat’s diet?” Well, most felines love the taste of fish, but some do not like fish, and some others have an allergy to fish. But in terms of health, is it really a good idea to add fish to a cat’s diet? Read on to learn more!


Do cats eat fish?

Cats evolved from ancestors that lived in the desert region, and their primary diets were reptiles, mammals, and birds. They never had a lot of access to fish.

So from an evolution standpoint, you can clearly see that cats do not have a “need” for fish. But you might say, “ancient cats also did not use items like litter boxes.” You’re right’ history is not enough reason to say something is bad for cats. But there are other notable reasons why you should have a rethink before adding fish to your cat’s diet.

Heavy metals, histamines, toxins

Fish contains a high amount of histamines – compounds released by white blood cells to tackle inflammation, which is helpful, but histamines also trigger many annoying allergy symptoms.

Cats could react to histamines, just like humans. So adding fish containing a lot of histamines is like exposing them to a possibility of allergic reactions.

Veterinarians consider fish to be one of the foods that trigger allergic reactions the most.

What about toxins? Fish can swim in polluted oceans and rivers, and much evidence shows that they might be picking up serious toxins while living in these habitats. The two major concerns for cats and also humans are pesticides and PCBs.

A substance called domoic acid, which is a heat-resistant toxin produced by certain algae species is becoming common in coastal regions due to climate changes. This toxin accumulates in clams, mussels, scallops, and fish. And research has shown that domoic acid causes damage to the kidneys at concentrations 100 times lower than the amount that could cause brain damage.

Because domoic acid is so dangerous, FDA limits the amount of this toxin in seafood. But the problem is that fishes that are condemned for human consumption may be processed into cat foods and this could cause chronic kidney disease, especially in older cats.

Also, many fish species have a serious problem with heavy metal contamination. Swordfish and sharks, for example, are always contaminated with magnesium and mercury – heavy metals that doctors usually advise women of childbearing age to avoid like a plaque. So if you wouldn’t feed it to yourself, why add it to your cat’s diet?

Fish contributes to a balanced diet

Fish is not entirely bad, so don’t be scared. It is useful as part of a balanced diet. And there is much evidence showing that you can get a lot of health benefits from eating some nutritional components of fish.

Fish is a great source of protein that is very usable by cats’ bodies. It contains the essential amino acids in the ratio we need them, although it may not be an exact match.

However, the main trick is moderation and choosing the right way to add fish to your cat’s diet.

There are lots of canned cat foods that come in “fish” flavors, but they mostly contain fish by-products like scales and bones and a hodgepodge of fish. These canned foods having bones are usually high in magnesium and phosphorus, which can cause issues in cats with a history of kidney disease or urinary tract disorder.

More so, there is a known link between feeding cats fish-based canned foods and the development of hyperthyroidism in senior cats.

So the advice is that if you want to feed your cat canned fist, ensure you give them single-ingredient stuff and don’t make it often.  

However, avoid fish like Tuna and Tilefish as they are part of the most heavily contaminated species.

It is not entirely bad to feed your cat real, skin-on fish when you want to give her a briny treat. Just make sure the fish you’re giving your cat is what you as a cat owner can eat too. And ensure the fish is free of bones.

One good thing about adding fish to the diet is that these foods are rich in heart-healthy omega-3 and Omega-6 fatty acids. So fish can help your cat stay on track.

But never give your cat raw fish as it can contain harmful pathogens.

And one more thing- Cats that primarily eat fish are at a high risk of having thiamine deficiency. Thiamine is a necessary vitamin that’s added to most foods sold commercially.

So, here’s the advice – It is okay to add fish as an occasional treat, and your cat will be fine.

Technology’s involvement in getting the best from fish

Recent technologies have made it possible to extract the best nutrients from fish and add them to cat foods. One “super-nutrient” found in fish such as Tuna and Mackerel is “fish oil”. This oil is now commonly isolated using technology and added to cat foods.

Many studies are already publishing the health benefits of fish oil for cats. This oil is good for your cat’s eyesight and brain.

Libby Sheridan, a veterinary surgeon from Hill’s Pet Nutrition, explains that “One particular fish oil (DHA) is involved in neurological development. This oil supports the development of the brain and its connections.”

The brain of a kitten has to remain “plastic” to gather all the information being assimilated from the surroundings as they hear, touch, see, and experience a whole raft of new things. Food supplements that contain DHA that helps your cat’s brain development, making them more alert and adaptable.

The need for balance

There is a balancing act going on in the body with respect to fatty acids – omega-3 and omega-6. A valuable form of omega 3’s is found in fish and vegetable oils. However, each group keeps the other groups’ effects in check. So that’s more reasons why you need to create a balance. Giving more of one kind and less of the other produces a different effect entirely.

A diet that is high in animal fat, for example, is believed to result in more omega 6 compared to omega 3. And there might be scope for cats to eat more omega 3s and stay healthy.

Hence, here’s a few words of caution- Don’t be tempted to give extra fish oil to your cat. When you add too much of a nutrient, it can distort balance and cause problems.

The best thing to do is to get veterinary advice before supplementing your cat’s diet, especially in cases of illness. Most times, your vet can prescribe a correct formulation or special that that can meet your feline friend’s specific needs.


Fish is a good food to add to any diet as they are rich in proteins and nutrients necessary for healthy growth and development. However, when it comes to your cat’s diet, you need to be careful. Fish is a high-risk food and can contain histamines, toxins, and heavy metals.

However, fish oil, which is a useful component of fish is now isolated using technology to supplement cats’ diets. You need to be careful here and don’t be distracted by the glamour-puss on labels when shopping for cat food.

Buy from reputable brands, and read labels to be sure the right oils are used, and they are sourced from the right kind of fish and unpolluted waters.

Lastly, always remember to consult your veterinarian for the best advice.



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