Why in super cold weather, only the top layer of the pond water freezes? and to add

[sean t]

on, the fish do not die? need help to answer this in chemical terms, chemical bonding etc. Help is greaty appreciated,, i nid the answer urgently THX!

[karen h]

check this site out. for "only the top layer of the pond water freezes" if you want more chem terms

and for the fishes.
Plants and animals can live under ice because of water's unusual quality of being most dense at 4 degrees C. Ice has a density about 93% of water so it floats on top. Water is most dense at 4°C. Deeper water below the ice stays at 4°C because colder water rises to the top due to its lower density. So at the bottom of a frozen lake, stream or pond, it's always 4°C, warm enough for life-or hibernation at least.