During the Northern Song Dynasty, fish farming in the middle reaches of the Yangtze River began to develop. Fishermen in Jiujiang and Hukou built pond culture, and their annual income ranged from several thousand to tens of thousands.
During the Southern Song Dynasty, Jiujiang became an important fry producing area. Every early summer, local people catch fry and sell them for profit. Traffickers have exported fry to Fujian, Zhejiang and other places so far, and have formed a series of mature experiences in fry existence, wild clearance, transportation, feeding and breeding.
South of Huiji and Zhuji, large households dig ponds to raise fish. It often costs tens of thousands to buy Jiujiang fry for breeding every spring. At this time, fish farmers put bighead carp, silver carp, carp, grass carp, herring and other fry in the same fish pond, and the earliest polyculture appeared.
In the Song Dynasty, goldfish were also bred, which is a unique ornamental fish in China. With the development of fish farming, the prevention and treatment of fish diseases began at this time.
Fish farming in Yuan Dynasty was greatly affected by the war. In this case, the Minister of Agriculture of the Yuan Dynasty ordered "living by the water and digging ponds to raise fish". Agricultural books published by agronomist Wang Zhen also promoted fish farming in China. The book "Fish Culture Classic" introduces the construction, management and breeding methods of fish ponds.