Antarctic Fish Live With Ice In Their Veins Year-Round

Nototheniod fish swims at McMurdo Sound. Photo: Paul Cziko courtesy University of Oregon Native fish species that brave the frigid waters of the Antarctic have ice in their blood, literally. To survive in the coldest climate on Earth, Antarctic notothenioid fish have specialized anti-freeze proteins in their blood that bind to ice crystals and inhibit their growth, keeping these fish from turning into fishcicles. Paradoxically, however, a new study finds that these same proteins also prevent ice crystals from melting, leading to a buildup of ice in fishes' veins that persists year-round and could be harmful to their health.