Abstract

Induced water flows stimulating the fish to swim can improve growth and feed conversion efficiency of cultured fish, but the effects of this treatment on water qualities in fish pond is not known. In this 4-week experiment, the effect of water flow (1.0 m/s) on the levels of total nitrogen (TN), total phosphorus (TP), total ammonia nitrogen (AN), nitrite-nitrogen (NO²⁻-N), nitrate nitrogen (NO³⁻–N), ortho phosphorus (PO43--P), and total suspended solid particles (TSS) in water of ponds culturing largemouth bass (Micropterus salmoides) were explored. The results showed that as compared to the control, the recirculation flow could reduce the concentrations of TAN and PO 3--P in fish pond water, but increase the concentrations of TN, NO₃--N, and TSS. There were temporal and spatial variations of water qualities in fish ponds under the condition of induced water flows, especially temporal changes of TN and TSS levels and spatial changes of NO₂--N and PO 3--P levels. It indicated that the growth-improved recirculation flow treatment did not deteriorate the water qualities and largemouth bass could generally grow in such environment.

Keywords: Water flow; Water quality; Micropterus salmoides; Pond culture