Fish living in frozen waters breathe under the ice using special mechanisms. In frozen water, the oxygen content is reduced, so the fish need to adapt to survive in such conditions. One way fish breathe under ice is to use the gill breathing holes on the fish's head. Gills help fish get oxygen from the water. Fish can also use the skin on their gills to extract oxygen from the water. In addition, some fish may move to the surface of the ice to obtain oxygen from the atmosphere. They can use the jagged protrusions on their heads to make a hole in the ice and penetrate the atmosphere. Thus, fish can survive in frozen bodies of water using a variety of breathing mechanisms that allow them to obtain oxygen from the water and atmosphere. How long can fish live under ice without oxygen? The water under the ice contains less oxygen than the water in the open, so it can be difficult for fish to get enough oxygen to survive. The length of time a fish can survive under ice depends on several factors such as the size of the fish, water temperature, water quality, and the amount of oxygen in the water. Small fish such as perch, walleye and pike can survive under the ice for weeks or months if the water contains enough oxygen and other vital substances. However, larger fish such as salmon or catfish require higher levels of oxygen and can only survive a few days or weeks. In any case, keeping fish under ice is not recommended as it can lead to stress and potential death of the fish. If you want to keep your winter fishing catch, it is best to periodically check the condition of the ice and ensure that there is enough oxygen in the water using special pumps or other means.