Why You Should Never Thaw Frozen Fish in Its Vacuum-Sealed Packaging

There's a lot to love about individually wrapped pieces of frozen fish: they're easy to store, prepare and portion.

But what if we told you that those handy vacuum-sealed filets also pose a huge hidden health risk? Eeek!

Few people realize that thawing fish in its packaging presents a high risk for botulism.

Clostridium botulinum is an anaerobic bacteria that forms spores that allow it to thrive in low-oxygen environments—like the ones created by vacuum-sealed packages. When the right conditions are present, the spore can produce a deadly toxin. That toxin causes botulism, a life-threatening disease that attacks the nervous system.

The warmer the temperature, the quicker the toxin forms. And when temperatures rise above 38 degrees Fahrenheit—i.e., the moment you remove it from the refrigerator—the risk for botulism increases greatly.

Luckily, exposing the fish to oxygen by removing it from its packaging can stop the spores in their tracks.

According to the Food and Drug Administration, the safest way to defrost your frozen fish is overnight in the refrigerator (the temperature should be set below 38 degrees anyway), but if for some reason you take an alternate route, always remove the packaging first.