Question

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

Answer 1

Water shows anomalous behaviour between $0^{\circ }C$ to $4^{\circ }C$. In between this temperature, the water expands instead of compression. Thus, it remains in a liquid state between temperature $0^{\circ }C$ to $4^{\circ }C$.

Underneath the frozen upper layer, the water remains in its liquid form and do not get the freeze. Oxygen is trapped beneath the layer of ice. As a result, fish and other aquatic animals find it possible to live comfortably in the frozen ponds.