Will goldfish freeze to death in cold weather?

If the river freezes, the fish will not freeze to death, but will only suffocate and lack oxygen!

Lying on the ice eating carp is based on this principle. When there is a hole in the ice, the fish will swim in this direction to breathe fresh air. So you can fish even without bait at this time!

In the cold winter, the freezing process of the lake begins from the upper layer of the lake, and the ice layer gradually thickens. If the temperature above the lake is -20℃ and the water temperature at the bottom of the lake is (4)℃. (Water has the highest density at 4℃, which I think only means that water at 4℃ must be at the bottom, not at the bottom. )

You should know that it freezes from the top, because it is a way of heat transfer-heat conduction, that is, contact heat transfer. Water slowly cools down from the surface and condenses into ice. As for the water temperature at the bottom of the lake, it is indeed 4℃. You can analyze it like this: water has the smallest molecular spacing and the largest density at 4℃; Then, consider a question, what is the temperature of the layer of water between the lake surface and the bottom of the lake? Dense water sinks at the bottom. Obviously, the temperature of the lake is lower than or higher than 4℃. If it is higher than 4℃, the surface temperature of water at -20℃ will gradually cool to 4℃ and sink to the bottom. Or, below 4℃, it is obviously the middle layer of the lake, and the water below will raise its temperature to 4℃ and sink to the bottom.

In other words, the temperature at the bottom of the lake is indeed 4℃! Of course, the above analysis cannot last forever. This is a logical question. It's all sunk to the bottom What's left on it? Obviously, there is a balance point in this process, and that balance point is that the water temperature at the bottom of the lake reaches 4℃.