Fish is trying to find access to oxygen in the ice-hole swimming "walrus" in one of the ponds Victory Park in St. Petersburg.
In winter, the artificial urban ponds under the ice due to the small amount of water stagnation occur. Especially in this time of suffering small fish in polluted waters, where the image of anaerobic (airless) conditions can be released methane gas, as well as in shallow ponds, freezing almost to the bottom. A consequence of the lack of oxygen becomes fish mortality.
If severe frosts will last a few days, and finally freeze hole, the fish in the pond seems doomed to extinction.