How much tuna is safe for a cat? [duplicate]

Question

Me and my wife has recently got a male 9 weeks old kitten. It comes from a good house, so it's already been treated for fleas and (most importantly) litter trained. According to its old owner, it used to eat pretty much any brand of wet and dry food.

However, the first days we had it it refused to eat anything at all we gave it. It didn't seem stressed or scared, just refused to eat even though it was begging for food. Then I tried putting some canned tuna in his wet food and, lo and behold, it ate the whole lot in a jiffy. In the meantime we also managed to find a brand of dry food it eats, so now he has that too.

Now, I know that you shouldn't feed a cat just canned tuna because of mercury accumulation and supplement deficiency, but the latter shouldn't be a problem as it's mixed with regular cat food. So, my question is:

How much canned tuna can a cat eat per day? We're using Lidl (UK) branded tuna in spring water, Here's some pictures of ingredients and nutritional values. It eats approx. between 10g and 15g of tuna per day (I've actually weighted it).

I don't mind adding tuna to its food for the rest of its life, as long as it's safe for it. Thank you.

Answer 1

Mercury is a cumulative poison, meaning that if you eat it even in small amounts but on a regular basis, it will build up and cause harm. As a result, generally speaking, the higher up in the food chain the fish is, the more mercury its likely to have because it accumulates it from the prey its eaten. Tuna are top predators, and as such, canned tuna is particularly bad for mercury. The FDA recommends at most one serving of canned tuna (8 to 12 ounces) for a HUMAN once a week for this reason. https://www.epa.gov/fish-tech/epa-fda-fish-advice-technical-information

Doing the math, what you're feeding your cat is at the higher end, as much as about 3.5 ounces a week. Cats being so much smaller than humans, I can only conclude then what you're currently feeding your cat is probably too much in the long term.

My suggestion is to cut out the tuna entirely. If your cat is still being reluctant to eat the cat food, make this transistion gradually over the period of a few days. Add less and less tuna each day until the cat accepts the regular food. If that doesn't work, you may have to accept the cat will only eat the kibble.