What is Carbon Monoxide Doing in Your Tilapia Filet?

Tilapia FiletCarbon monoxide (CO) is a clear odorless gas that is lethal to humans in large concentrations. It’s one of the gasses that’s emitted from a car’s exhaust pipe. That’s one of the reasons you should not run you car inside a closed garage.

Carbon monoxide has another interesting property – it can be used on meat and fish to make them look more fresh: the CO molecules delay the discoloration of the flesh that would otherwise indicate it is starting to rot. There is also a small benefit in gassing – it kills some potential parasites. Tilapia, a relatively cheap and healthy fish, reacts very well to treatment with CO. It can be frozen, shipped halfway across the world, and then, when thawed, be put on display and appear “just caught”.

The amount of gas used is tiny, and it does not pose any direct health risk.The problems begin when you buy a fresh looking fish that really isn’t that fresh. Regardless, the European Union and China forbid CO treatment of food. And in the US? you know the answer…

Americans eat about 500 million pounds of tilapia each year. The US sources tilapia mostly from Latin America and from China. Almost all tilapia is farmed. The fish from Latin America are not gassed, the fish from China are. Yes, the Chinese government allows gassing for export, but not for local consumption.

You’re probably thinking, “next time I go shopping, I’ll choose the tilapia from south or central America”. The problem is that in most cases, the origin of the fish is not labeled. Since the amount of tilapia imported from China is about ten-fold what we get from Latin America, it is safe to assume you are getting tilapia+CO.

Bon appetit.

  • lhq

    so what would be the alternative

    • derf

      Eat the fish that China eats I guess, America doesn’t care about it’s citizens anymore.

      • Marlene

        have lunch in China

  • Emily

    Buy sustainable fish that doesn’t come from farms. Wild caught.

    • Linda

      It can be hard to find and is definately more expensive. Does curb my eating of fish these days when all I can find in the market here is from Asia. And I live less than an hour from the gulf — crazy world we live in now.

    • Elizabeth Harris Carter

      Where can I buy it wild caught?

    • Dan

      Since when does wild caught = more sustainable?

      I think the better statement is “Eat Sustainable Fish.”

      Take Artic Char for example. It is only available farm raised and it is one of the most sustainable fish on the market. Our food system is not a system of absolutes.

  • ginger_katz

    CO (carbon monoxide) is lethal to animals in relatively small concentrations, not large. For humans the lethal dose is about 1600 ppm. CO is colorless, odorless, non-irritating, all of which make it extremely dangerous. That’s why you should have a CO detector in your house. CO is dangerous because it binds to hemoglobin (the protein in red blood cells that normally carried oxygen) more efficiently than oxygen. When CO binds to hemoglobin, the complex turns a bright red, just like the oxygen complex. Red meat in the USA is also treated with CO to appear fresher than it is.

    • djc263

      It’s also naturally occurring in the atmosphere, The question is how much? at no point in history has the answer ever been truly zero. We tolerate tiny amounts just fine.

    • Gagavagavavava

      … When it is inhaled. Does the same go for ingestion? I don’t know, but probably not. I’m guessing the CO is metabolized before it gets to the duodenum.

    • Jacqueline M

      I am SO frickin’ upset. My dogs and cats LOVE the Walmart Tilapia fish and I once gave my small dog two, raw, entire pieces.

  • Steve Brunell

    the author is incorrect. You would know where the product comes from. Retailers are legally required to post the Country of Origin and Method of catch (farmed or wild).

  • Elizabeth Harris Carter

    It’s illegal for consumption in China but they use it to ship fish to America? RED FLAG!

  • LotusFlowerBombOne

    America so petty.

  • Branded

    Well my innocence is gone America I thought was the best smartest most beautiful nation filled with intelligent people who looked out for us but I am wrong

  • gandaalf

    We’re making a mountain out of a mole hill. The carbon monoxide (CO) in the fish is NOT the problem. The real problem is that the presence of the CO could mask indicators that would tell you the fish has not been handled properly. It could look fine, and smell fine, but still have gone bad. Buy from a reputable store, and practice good handling yourself, and you can enjoy your Tilapia. Alternatively, you can buy Tilapia that has already been processed, not fresh, and it won’t be an issue.

    • Samuel F


  • Jacqueline M

    Of course they ship their crap to us and laugh all the way to the bank. F*ck them, and there should be a national screw China day when NO ONE buys Chinese-made/imported products. What happened to America, guys?

  • Bonnie

    I’m not surprised…. So many things tainted in America