Ice fish are a unique group of fish found in Antarctica. Ice fish have evolved a variety of interesting physiological and biochemical adaptations that allow them to survive in the freezing, ice-laden waters of the Southern Ocean at temperatures that would freeze the blood of other fish. They do not have a swim bladder, and they spend much of their time near the ocean floor. To help them survive in the very cold waters, they have antifreeze proteins in their blood and body that keep their cells from freezing. Because of the high oxygen content in Antarctic waters, the ice fish are able to survive with lower amounts of hemoglobin, the protein that carries oxygen to the rest of the body, than other fishes. They have a larger volume of clear blood instead and this gives them an unusually ghostly white color, particularly their gills.
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