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Asked by anon-371118 to Clemence on 9 Nov 2023.
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Clemence Fraslin answered on 9 Nov 2023:
Fish are ectothermic also known as “cold-blooded” which mean their body temperature adapt to the water temperature (not like us, our body is suppose to stay around 37 degrees, more means you have fever). So I don’t think fish can die from cold and froze. However is the water is frozen around the fish they’ll die after a time (they need oxygen in the water and to eat).
Also depending on the fish specie they like certain range of temperature, for example rainbow trout prefers cold water (10-14 degrees), and they faint at warmer temperature (24 degrees) whereas Tilapia like warm waters.
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Comments
Clare commented on :
Good question! Ice floats so even if the ocean freezes there is still water underneath it. And this water might still be quite warm.
Anton commented on :
There are lots of things about this question that make it interesting and very difficult to answer in full.
A fish trapped in shallow water will die if the temperature falls so low that all the water freezes and the temperature of the ice falls low enough.
A similar question is why don’t fish die in the cold waters of the Antarctic ocean? Here, the sea may be covered by floating ice but below the ice the salt water is still liquid at about -2ºC. The salt lowers the freezing point of seawater so that it does not freeze at this temperature. Some of the fish that live here have a sort of anti-freeze in their blood that stops it freezing solid.