Overall , about one - sixth of the world 's protein is estimated to be provided by fish .
However , aquaculture , or fish farming , which has been practiced since about 3,500 BCE. in China , is becoming increasingly important in many nations .
About one - sixth of the world 's protein is estimated to be provided by fish .
However , aquaculture , or fish farming , which has been practiced since about 3,500 BCE. in China , is becoming increasingly important in many nations .