Is fish bad for cats?

Is fish bad for cats? I hear that question a lot since our Sealy is hooked on Whiskas Purrfectly Fish. He’s also eating their chicken and beef flavors now to wean him off so much fish. As it turns out, a lot of us are turning our cats into “fish junkies.”

I guess the best answer to this question lies not only in what kind of fish we’re talking about and how often it’s fed to your cat.

Feral cat with a fish in mouth

Feral cat with a fish in mouth

WebMD states that tuna made for human consumption is okay for a treat every now and then. But regular tuna isn’t formulated with the vitamins a cat needs to stay healthy and it also carries a risk of getting too much mercury in the diet.

Too much tuna in your cats diet can cause steatitis, which is a yellow fat disease caused by too much unsaturated fat in the diet. Tuna food made specifically for cats isn’t 100% tuna and is considered safer than that made for humans. Keep in mind studies are now showing tuna(and other fish cat foods) may cause an increase in crystal formation and shouldn’t be given to a cat with urinary problems.

Note that albacore tuna made for human consumption isn’t a better choice for us or our cats. It’s made from larger tuna, who have had the opportunity to absorb more mercury into their system before we turn them into a sandwich or a meal.

Many cat owners who feed their cats human grade tuna claim their cats are addicted and refuse to eat any other food. This isn’t good since the tuna isn’t nutritionally balanced for a cat. We’re thankful Sealy doesn’t have that problem. He’ll eat anything we put in front of him.

Research shows not only magnesium levels in tuna are too high for cat consumption, it affects the pH level of the urine and that’s why crystals form. Some canned fish food for cats advertise lower magnesium levels. PBDE levels (polybrominated diphenyl ethers) found in fish have also been shown to cause an increase in hyperthyroidism in cats.

Both fish and beef are common food allergens in cats and can also cause skin conditions.

Raw fish is an even worse choice. Many people have switched their cats over to a raw meat diet and the cat has benefited. This doesn’t hold true with raw fish for several reasons.

Raw fish is high in phosphorus and may cause kidney problems. It’s also full of thiaminase, an enzyme that destroys Vitamin B-1(thiamin). You also have the danger of the same contaminants as with tuna.

While raw fish is high in some bad things, it’s also low in nutrients a cat needs to stay healthy. Namely calcium and Vitamin E.

This goes to show a cats natural diet is really what’s best for them. Cats don’t go fishing in the wild. Think small prey such as chicken, turkey or even mice(these can be ordered freeze dried). Whether you purchase these canned or fresh to feed raw or cooked, stick to land animals and cut back on the fish.

Fish should be reserved as an occasional treat for healthy cats. Just be sure you purchase it in the cat food isle and not the meat department.

Have any of you had any trouble caused by feeding fish to your cats? Any withdrawal or refusal to eat when you took it away from them? Comments are always welcome.

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About Michael Broad

Michael is retired! He retired at age 57 and at Aug 2018 is approaching 70. He worked in many jobs. The last job he did was as a solicitor practicing general law. He loves animals and is passionate about animal welfare. He also loves photography and nature. He hates animal abuse. He has owned and managed this site since 2007. There are around 13k pages so please use the custom search facility!


Is fish bad for cats? — 1 Comment

  1. Hi Elisa, my late lady cat Binnie loved fish. She liked prawns as much as she liked microwaved fish. I don’t recall giving her raw fish. It was frozen plain fish that I microwaved. I also added water after cooking it. Not much, just a bit to make sure she ingested more water. This was a deliberate way of preventing the re-occurrence of cystitis. The extra water helped to flush out her urinary tract. I think the answer with fish is; if your cat likes it give it but not to excess in order to ensure the diet is balanced.

    The photo of the feral cat with a whole fish is interesting because feral cats often congregate at fishing ports. They must live off fish almost exclusively. Are these cats healthy? Or is their diet unhealthy?

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