Thawing Frozen Fish in This Way Could Be a Potential Health Risk

When it comes to defrosting any kind of meat, it’s important to be conscious. While many of us might just take the frozen slab from the freezer to the counter and let it sit out until it’s not frozen anymore, there are actually a lot better ways to go about this—especially when we’re talking about fish, and especially when it’s vacuum-sealed.

First off, we’re not knocking frozen fish. Purchasing vacuum-sealed fish is actually one of the best ways to ensure the fish is still fresh upon defrosting. It keeps the fish from drying out, locking all the moisture in and the individually-wrapped pieces are super convenient when you’re in a pinch for dinner.

However, it’s very important that when you do defrost vacuum-sealed fish that you remove the fish from the packaging before setting it out to thaw. Defrosting fish in this packaging can actually increase your risk of botulism.

What is botulism?

While rare, botulism is not to be taken lightly. It’s a serious sickness that’s caused by a toxin that attacks the body’s nerves. Symptoms of botulism include a feeling of weakness in your face, including your eyes, mouth, and throat, and potentially your neck, arms, torso, and legs. The bacteria can weaken your breathing muscles as well, which can make it difficult to breathe and in some cases, botulism can even lead to death.

So what’s botulism have to do with your vacuum-sealed fish? Well, one type of toxin, the C. botulinum toxin, comes about when spores allow it to breed in certain low-oxygen conditions, like a vacuum-sealed package. But not when frozen—when warm. As the temperature rises, so does the risk of the toxin forming. The scary mark is right around 38 degrees Fahrenheit.

The reason your risk of getting botulism decreases when opening the sealed package before defrosting is that the fish can then be exposed to oxygen, so the spores won’t produce the cells that form the toxin.

Image of vacuum-sealed frozen fish.

Additionally, thawing frozen fish in this way can also lead to an increased risk of listeria monocytogenes, or listeria.Wikimedia Commons

What is listeria?

Listeria, like botulism, is a bacteria that can grow on your food and cause you to get very ill. Symptoms can range from just from having a headache, to stiff neck, confusion, fever, and muscle aches.

It can also be fatal. About 1,600 people get listeriosis every year, with about 260 deaths, according to the Center for Disease Control and Prevention. People especially at risk include pregnant women, newborns, adults age 65 and over, and anyone with a weakened immune system.

To ensure that you don’t get any of these serious diseases—or any diseases at all!—take proper precautions when thawing fish, or any kind of meat. The best way to get seafood ready from freezer to cooking is to put it in the fridge overnight.

How to defrost fish the right way

For quick defrosting, place the fish in a plastic baggie and run it or immerse it under cold water. And if you’re planning to cook the fish immediately, the thawing setting on the microwave is safe, but be sure the fish is still icy when you take it out. You just want to loosen it a bit so it’s pliable and easy to manage.

Did you know that thawing out vacuum-sealed fish could be so harmful? Have you ever done it before? The more you know!