Elman artificial neural network model was developed to predict the change of water NH_3-N in aquaculture pond. The indexes including feed ration,dissolved oxygen in water,water temperature,air temperature,water turbidity,rainfall were recorded and chosen as the input variables,while the NH_3-N content in the corresponding pond was chosen as output variable. The above data were collected everyday from June to October in 2014. They were used to develop model in this test,and the data collected in November of ...