Huazi fish struggle upstream to reproduce

Huazi fish, or Leuciscus waleckii, in Dali Lake in Chifeng, Inner Mongolia autonomous region, swim against the current to lay their eggs in fresh water upstream from mid-April to early May every year. Large masses of fish flow in the water to form a quick-moving black shadow that can stretch up to 5 kilometers at peak times. Such movement is dangerous for the fish, as they must overcome obstructions, such as rocks, as well as threats from birds, which see them as food.

[Video by Meng Zhigang]