How Do Fish Keep From Freezing During Winter?

It's the middle of winter in the Northern United States and temperatures have been consistently below freezing for weeks. A few fishing buddies talked you into a day of ice fishing on the lake, so now you're sitting in a shanty, sipping on your warm morning coffee and wondering, how in the heck do fish survive all winter long in such chilly water temperatures anyway?

There are actually a few factors involved when it comes to answering the question of how our finned friends manage to stay alive and swimming during the winter… even when the wind chill factors dip well below zero. Here are a few examples:

  • During the winter months, in most cases, only the upper few feet of water will freeze solid (ice thickness will depend on the specific region and weather conditions). When the upper layers freeze, they actually help act as a barrier or form of insulation between the cold air and warmer water beneath. This keeps the water fluid beneath the upper layers of ice and fish can live comfortably there. One important note regarding ice thickness to consider: Always check to be sure that the ice is at least 4 inches thick and can support your body weight before you start fishing.

  • When it comes to the wind chill factor, keep in mind that even when the winter winds blow fiercely above the ice and cause the air feel even colder than it actually is, the wind doesn't have that same effect beneath the ice.

  • Water temperature also has an effect on fish respiration and metabolism. In winter, when the water is cold and there is less food is available, the rate of respiration decreases because fish require less oxygen as their metabolism adjusts. This is why fish do not exert as much energy, move as fast or fight the same way as they do during warmer months.

Now that you know a little bit more about how fish survive during the coldest months of the year, why not learn a few new ice fishing techniques that you can apply the next time you plan to spend a few hours in a shanty? Then, once you catch a nice fish through the ice, don’t forget to post your favorite photos to our community photo gallery.

Debbie Hanson

Debbie Hanson

Debbie Hanson is an award-winning outdoor writer, women’s sport fishing advocate, IGFA world record holder, and freshwater guide living in Southwest Florida. Hanson’s written work has appeared in publications such as Florida Game & Fish Magazine, BoatUS Magazine, and USA Today Hunt & Fish. To learn more about her work, visit or follow her on Instagram @shefishes2.