Near the Filchner Ice Shelf in the southern Antarctic Weddell Sea, a research team has discovered the world’s largest colony of fish. The discovery is reported in the journal Current biology.

Researchers have discovered 60 million icefish (Neopagetopsis ionah) nesting sites in the Weddell Sea, each guarded by an adult. Each of them contains an average of 1,700 eggs. It turned out to be the largest known colony of breeding fish. The peculiarity of ice fish is that their blood and most of the body are transparent. They are the only vertebrates that do not have red blood cells. To survive in low temperatures, they are helped by the production of a special protein that prevents ice crystals from forming in the blood.

The population was noticed by scientists who conducted research aboard the German icebreaker RV Polarstern. One of the ship’s missions was to monitor the seabed of the Weddell Sea. On the video, scientists accidentally noticed fish nests, it turned out they occupied an area of ​​​​240 km² – it is comparable in size to Malta. The central area is lined with small stones, the depth of the nest is 15 cm, the diameter is 75 cm. Each such hole can contain from 1,500 to 2,500 eggs.

One of the questions the researchers want to answer is how long adult fish guard the eggs (experts suspect it could last for months) and who acted as the “watchman” – the male or the female.