Fish Tries To Get Oxygen, St. Petersburg, Russia

Fish cluster at an ice hole, covered with thin pieces of ice, struggling for air in a pond in a park in St. Petersburg, Russia. As the long Russian winter drags on, fish in the ponds become increasingly desperate for oxygen, clustering in vast, thrashing masses at shrinking holes in the ice. Not only does ice block oxygen that could be diffused into the water from the air, but it also impedes sunlight from reaching oxygen-generating plants and algae in the water.
For example, the Antarctic icefish belong to the perciform suborder Notothenioidei and are the largely endemic, dominant fish taxa in the cold continental shelf waters surrounding Antarctica. At present, the suborder includes 8 families with 43 genera and 122 species. Although the Southern Ocean is relatively well sampled, new species of notothenioids are still being described.
The majority of Notothenioids live at seawater temperatures between of –2°C and 4°C, but some sub-polar species inhabit waters that may be as warm as 10°C around New Zealand and South America. It is possible to have seawater temperatures below the freezing point of fresh water (0°C) because dissolved salts lower the freezing point of a solution in a colligative manner.