Experimental study of the effect of hydrodynamic conditions on fish growth

To find out the appropriate hydrodynamic conditions for fish growth is an important issue in present eco-hydraulic research. The experimental study presented here is to investigate the effect of the hydrodynamic conditions on fish growth. Especially, the Carassius auratus is chosen here for the case study through taking segmentation experiments in the graded ring shape flume. The detailed hydrodynamic characteristics of flumes which are relevant to fish growth are obtained through the 3D numerical simulation of the flume's flow field. Compared with the simulation results and the on-site measurements, the simulation is shown to be reliable. Combining the relative daily growth rate of Carassius auratus with the flow detail characteristics which are quantized by three hydrodynamic characteristic variables including flow velocity, velocity gradient and kinetic energy gradient, the quantitative relationship is established between the fish growth and the hydrodynamic characteristic variables. There is a short-term effect of flow velocity stress on the growth of Carassius auratus, and 0.2m/s is a very feasible velocity for the growth of Carassius auratus. A negative correlation is found between the relative daily growth rate and the kinetic energy gradient with the relative daily growth rate decreasing with the increase of kinetic energy. The threshold of kinetic energy gradient of the growth of Carassius auratus is 0.009J/(kg·m).The quantification of the hydrodynamic conditions of fish growth can provide the quantitative basis for the ecological water conservancy planning.