Abstract:

Abstract: Total nitrogen (TN) and total phosphorus (TP) are the most important factors causing eutrophication, while ammonia and nitrite are the two key environmental factors causing fish disease. In this experiment, we studied the control of nitrogen and phosphorus to tilapia fish pond by floating-bed-grown water spinach (Ipomoea aquatica) consisted of PVC tubes. The results showed that, by the later stage of the experiment, the concentration of TN decreased to the second standard of the waste water of freshwater fish pond, the concentration of TP achieved to the second standard of environment quality of surface water, while the concentration of ammonia and nitrite decreased to 1mg/L and 0.1mg/L below respectively. In the terms of the area of the test-groups, the nitrogen and phosphorus removal of time – depend and area- depend of floating-bed-grown was evident, the more the time lasted, the better the effect of area- depend. The results also showed that, floating-bed-grown water spinach had a good effect in the control of nitrogen and phosphorus in intensive- aquaculture fish pond, and when the area of floating-bed was 20%, the economic benefit achieved to the optimum level. This experiment offered a new thought to the health breeding of freshwater fish pond.