Abstract:

Studies on effects of culturing density on behavior and immunity of the Chinese sturgeon 〖WTBX〗Acipenser sinensis〖WTBZ〗 and the effects on the water quality of their living pool were reported in this paper.Six wild sturgeons and 62 offsprings were cultured in three different living densities of 27,24 and 20 kg/m3 respectively in Beijing Aquarium between 2008 and 2009.Behavioral observation showed that the distribution of swimminglevel of fish changed at different culturing densities,and the behavior of younger fish changed more frequently.The sturgeon’s appetite didn’t show much difference in different densities.Swimming speed and respiratory frequency of wild sturgeons and #F11998 didn’t changed either.On the other hand,SOD,SOD/MDA and GSHPX of serum of #F11998 decreased,while MDA increased at the density of 27 kg/m3.The older fish including wild and #F11998 were infected by bacteria at the densities of 27 and 24 kg/m3 when the total bacteria numbers were continuously higher than 8 000 cfu/100 ml.With the decrease of density,NH3/NH4-,NO2- and turbidity did not fluctuated significantly,NO3-,PO43- and total bacteria number declined,while DO and pH increased,and there were significant differences (〖WTBX〗p〖WTBZ〗＜001) among these parameters at the three different densities.NO3-,PO43- and total bacteria numbers were positively correlated significantly with the density.These results indicate that the effect of the environmental capacity on the aquatic microbial communities and the fish immunity is significant when the sturgeons are cultured in recirculated water system.An optimal culturing density is drawn at 20 kg/m3 from this study