FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

This study aimed to find the best zero-exchange culture model for white shrimp (Litopenaeus vannamei). Shrimps were cultured in FRP tanks (2 m×2 m×1 m), and organic particles were suspended by strong aeration. The following three experiments were conducted: (1) substrate: net-liners, net-pockets, mats, coral granules and blank control; (2) density: 100, 200, 300 and 400 ind./m2; and (3) zero-exchange water and exchange water (35% ponds of water / week). Shrimps cultured in tanks with net-pockets exhibited the highest yield and average weight gain and the best FCE, while net-liners isolated the highest amount of suspending particles. The average weight gain of the shrimps was decreased as the stocking density was increased; furthermore, they grew more slowly when the density was in excess of 200 ind./m2. Orthophosphate phosphorous concentrations of the zero-exchange system were significantly higher than those of the exchange system. The inorganic nitrogen compounds were all at safe levels. When compared with those of the exchange system, survival, average weight gain and FCR did not differ between the two treatments; however, the yield was higher in the zero-exchange system. In conclusion, shrimps cultured in a zero-exchange system with a density of 200 ind./m2 and a substrate of net-pockets produced the highest yield.