Water (molecule)
This property of volume decrease allows fish and other aquatic animals to survive in a body of water when ice has frozen on the surface. In cold climates, when the temperature of a body of water reaches at 4°C, the layers of water near the top in contact with cold air continue to lose heat energy and their temperature falls below 4°C. On cooling below 4°C, these layers rise rather than sink, as water has maximum density at 4°C. Thus the layer of water with a temperature of 4°C remains at the bottom, while layers of water 3°C, 2°C, 1°C and 0°C are formed above. Because ice is poor conductor of heat, it does not allow heat energy transfer from the liquid water beneath the layers of ice, which prevents the liquid water from freezing. Hence, aquatic creatures survive in such places.