This is the heartwarming moment a walker rescued fish that were stuck under the ice in a frozen lake .

Andreas Petersen noticed the school of perch trapped in the shallow, rocky water below the hardened ice surface of the lake in Gavle, Sweden.

The nature lover rushed home to grab a small claw hammer to break the ice and free the five stuck fish.

The creatures started wiggling when he smashed the ice, which allowed them to move again. In under a minute, they were able to dart away into the warmer depths of the lake.

Andreas made the caring rescue in January this year when temperatures plunged below zero but footage only emerged this month when he published it online for the first time.

Andreas said: "I rescued the fish while they are small but when they get bigger, maybe I will catch them again when I'm fishing.

''I'm happy because I was able to do something so simple to save them.''

Much like bears and other hibernating animals, some fish are able to shut down basic bodily functions, slow their metabolism, and enter a dormant state so they can survive when still water freezes.

This means that they mights have survived in lake until it started to melt, even if Andreas did not rescue them.