A muddy pond with thousands of tilapia could be 50,000 pounds of fish. I don’t think China worries too much about the quality of life for fish. Where do you think tilapia comes from?? haha.
Some info on fish farming from China. “While the usual pond fish raising may produce about 4 tons of fish per hectare, the integrated system may produce more than 10 tons per hectare (12.2–19.5 tons) or 2 to 3.9 times more.”
http://www.fao.org/docrep/004/ac155e/AC155E16.htm