In which country was a complex fish-farming system developed over 1,000 years ago?

The complex fish-farming system developed over 1,000 years ago in China represents a significant achievement in agricultural practices. This system, known as aquaculture, involved the intentional breeding, raising, and harvesting of fish and other aquatic organisms in controlled environments. The practices in ancient China were innovative for their time, integrating rice cultivation with fish farming. Farmers would flood their rice paddies with water, allowing fish to thrive while simultaneously providing ecological benefits such as pest control and nutrient recycling.

China's long history of aquaculture has made it a leader in fish farming, showcasing sustainable methods that have been practiced for centuries. This integration of agriculture and aquaculture not only improved food security but also contributed to various cultural and economic aspects of life in ancient China.

The other countries mentioned have their own rich histories related to agriculture and aquaculture, but the specific development of a complex fish-farming system over a millennium ago is most closely associated with China, marking it as a pioneering nation in this field.