Catfilter: do I need to be buying a wider variety of canned food?

August 28, 2023 11:42 AM

My cat is a cartoon cat who loves tuna and salmon canned food and sometimes turns her nose up at other things, so I buy all fish flavors in a variety of brands to mix it up. Now I'm reading here and there you shouldn't give you cat all fish. Is this legitimately another thing to worry about? She gets dry food (a mix of Taste of the Wild and Nulo's low cal stuff because she's a chonk) during the day and canned food at night.
posted by less-of-course to Pets & Animals (7 answers total)

Unless you buy mono-protein cans, a can labelled tuna contains not only tuna but some part will be for example "Meat & animal derivatives, Fish and fish derivative (Tuna 4 %) etc..."
So in the usual brands it is never just one kind of fish but a blend of meat and fish.
Now if you buy/feed mono-protein food, it is made with just that one protein, eg chicken, and this may be a problem.

In case you wonder how i know, i read myself through pretty much all the cat food ingredients lists on the website i order from. No joke. Main reason was i wanted to find a brand without sugar and carbohydrates. In the process i noticed how arbitrary the labelling as "chicken" or "salmon" is, they always contain a Mix. Unless labelled mono-protein.
posted by 15L06 at 12:08 PM on August 28, 2023 [2 favorites]

From what I've heard, the concern with feeding a lot of fish is that fish can be contaminated with mercury and other toxic heavy metals, especially fish like salmon and tuna that are high on the food chain.

Some people are concerned about it, some are not, we don't really know how much mercury cats are ingesting in their cat food or to what extent it poses health risks. This article, or the research it's based on, may be worth reading. (The research article is paywalled, unfortunately).

It's enough of a concern for me that I decided before I got a cat that I wouldn't feed her much fish. (Turns out, she doesn't like fish anyway!) But... it's really hard to know to what extent it's something that's worth being worried about.
posted by Jeanne at 12:28 PM on August 28, 2023 [1 favorite]

Vet Lisa Pierson says on her site catinfo.org:
"...it is not a good idea to feed fish to cats. Or, at least not as their main diet. Fish can be high in mercury, high in PBDEs (fire retardant chemicals linked to hyperthyroidism), high in phosphorus (not good for older cats’ kidneys) and can be very addicting. It is best to feed poultry-based diets."

Her recommendations seem to be backed by a lot of knowledge and experience, so I've always considered her to be a trustworthy source of info. She does say on the linked page that dry food is Bad and explains why; that tends to get people's backs up so I want to note that she's recommending what's generally best. You don't HAVE to follow all her recommendations perfectly and cats can do quite fine on suboptimal diets.

It's more like, if you'd like to make kitty's diet a little closer to ideal, cutting back on fish is a good idea. Or cutting it out entirely if Kitty won't eat poultry when she had fish last night. That might be a difficult process, I know how frustrating it is to buy a bunch of different brands of cat food and have them all refused. You could try mixing fish + not fish cat food with a little less fish each day and see if she'll go for that.
posted by Baethan at 12:49 PM on August 28, 2023 [2 favorites]

My cat is the opposite and dislikes most fish! I have noticed a number of mixed protein flavors like chicken and fish that you could try, or mix in a bit of fish flavored food into a different flavor? We also have, with previous cats, sometimes given them some water from canned tuna or sardines intended for humans mixed into their regular food (current kitty turns her nose up at this treat!) Also, larger fish like tuna are more of a concern with regards to mercury and pollutants than fish lower on the food chain like sardines, mackerel, or most shellfish like clams and shrimp. So you could lean towards those flavors.
posted by music for skeletons at 1:17 PM on August 28, 2023 [1 favorite]

I would say it's more on the phosphorous side of things that I would be concerned with feeding fish-based food to cats, because for cats who end up with kidney disease (a lot of them!) they have to be switched to a low-phosphorous diet to manage it and that very much means no fish.

I don't think it's that much of an issue right now, probably, but as your kitty gets older it could be. It might be a good idea to try to mix the food up a bit and gradually move away from fish-based foods now while you have some leeway, since most cats (and their humans) find the transition to a kidney formulation if they have to go that way a bit of a rough experience anyway.
posted by urbanlenny at 4:02 PM on August 28, 2023

From the view of a mostly-fish diet cat:

My cat is allergic to chicken, dried foods, and hates lamb. Guess what most of his diet is? I make sure to use mixed fish, as good of quality as I can find, and containing no chicken at all. It's.....really hard finding those specs and finding what he will actually eat, but it's out there. Especially when the fuzzy jerk will randomly decide not to like something he's been eating for a year.

I so wish he could eat chicken, as my food bill and time I spend contemplating his food, would be much lower. But 5 years in, his 2x a year vet visits have him in perfect health. The vet knows most of his diet is fish and beef, and have never urged me to do anything else. They are just happy he is eating and has no more digestion issues due to his allergies.
posted by haplesschild at 4:05 PM on August 28, 2023

I feed all poultry and beef with softened dry food because we are in the desert and dry food alone can promote dehydration. I use fish sparingly as smelly enticement when they are old and won't eat anything else. Fish has too much phosphorus, and impacts kidneys over time.
posted by answergrape at 8:45 AM on August 29, 2023