The water flow velocity in the suction pipe,which is crucial for evaluating the performance on pumping fish,can be measured by the pumped water flow rate of the riser in an air lift pump system.Several factors affecting the performance of water transportation were investigated through experimental methods in a water tank.Different designs involving six kinds of plane air injectors,two annular air injectors,five submergence ratios,three submergence depths and three sizes of riser were tested and water flow rates were recorded.Experiments on pumping live fish were also carried out.The results indicated that the D2 and D3 plane air injectors increased the pumped water flow rate due to its proper orifice distribution,but the difference between all plane air injectors was not distinct.The D6 annular air injector based on its ideal bubble size and distribution had the optimal capability for pumping water.Increasing the submergence ratio and the submergence depth or decreasing the diameter of the riser was determinant to improve the performance of the pump.Preferable capacity for pumping fish could be achieved while higher proportion of fish to water was kept in the fish-assembling device.