This passage from the newly released  State of World Fisheries and Aquaculture report for 2012 really brings home the point that China dominates global aquaculture production:

Asia accounted for 89 percent of world aquaculture production by volume in 2010, and this was dominated by the contribution of China, which accounted for more than 60 percent of global aquaculture production volume in 2010.

By volume, China accounts for almost two thirds of global aquaculture production.