In the coldest part of winter, check your pond every day. If the surface is frozen, carefully place a saucepan of hot water on it to gently melt a hole in the ice. Never tip boiling water straight onto the pond or break the ice with force, as this can harm or even kill any fish that live there.
Products are also available that can be used to help maintain a hole in the ice and prevent the build up of noxious gases in the water. These are available from some garden centres and from specialist mail suppliers.
Keep dogs away from frozen ponds and lakes, as thin ice can break under their weight.
Other useful information:
Breeding season for British frogs and newts
Caring for amphibians and reptiles as non-domestic pets
Dead frogs in a pond
Filling in a garden pond
Frogs and toads
Ice on a garden pond
Pond overcrowded with amphibians
Too much frogspawn in a pond