Question

How do fishes and aquatic animals survive when the pond gets covered with thick ice?

Answer 1

Water has an unusual physical property. When cooled, it first contracts in volume, as do other liquids, but at 4°C (maximum density), it starts expanding, and continues to do so till the temperature reaches 0°C, the point at which it freezes into ice.

The property of anomalous expansion of water enables marine life to exist in the colder regions of the world, because even when the water freezes on the surface, it is still liquid below the ice layer.