Mongolians have lived in northeast China for over 1,000 years. At Lake Chagan in Jilin Province, they have become fishermen - ice fishermen. From December to March, when it is freezing cold, they venture out onto the frozen lake every morning and launch a two-kilometer-long net. The time-honored custom is now a lucrative business. Fish from Lake Chagan, still free from pollution, fetch good prices - up to 110,000 euros for a bighead carp! With tools used by their forefathers and the pulling power of their sturdy horses, the ice fishermen unfold and move their huge net under the ice cover of Lake Chagan. In this way, Zhang Wen and his men catch between 80 and 100 tons of fish per day. But climate change has started to give them a hard time. There are also generational conflicts: the fishermen's sons have no desire to follow in their fathers' footsteps. In spite of the skyrocketing prices, the tough job remains poorly paid. *** On the day of the opening of the ice fishing season, fisherman Qi Yashen and his colleagues set out shortly after 4 a.m. For hours, they drive their horse-drawn carriages over the ice which is more than one meter thick. Their destination is a spot where their boss expects a good catch today. "Youbatous" (captains) like Zhang Wen guard the secret where and when one can expect the best catch in the huge Chagan Lake, which is one of the last remaining Chinese lakes that is relatively free from pollution. And it is famous for its abundance of fish. To keep it that way, the ice fishermen make sure that the mesh of their nets is wide enough to catch only large, adult fish. Zhang Wen, his "vice" Bing Hailong and their men are particularly interested in the big carp. Today, they are competing with three other teams for the biggest catch. Up to 20,000 spectators will be present when the first and largest fish are auctioned off to the highest bidders. Will Captain Zhang Wen's team be the best again?