封闭型水体中养殖密度对罗非鱼生长性能和水质的影响

Effects of Breeding Density of Oreochromis mossambicus on Growth Performance and Water Quality in Confined Water

关键词:  罗非鱼  养殖密度  生长性能  零换水  水质

Key words:  Oreochromis mossambicus  culture density  growth performance  zero water exchange  water quality

摘要:

为探究室内零换水条件下罗非鱼(Oreochromis mossambicus)养殖达到上市规格的最适宜密度水平，本试验设置4个密度梯度，养殖持续135 d，研究不同养殖密度对封闭型水体中罗非鱼的生长性能及养殖水体水质的影响。结果显示，随着养殖时间增加，低密度组的终末体质量(Final Body Weight，FBW)、增重率(Weight Gain Rate，WGR)、特定生长率(Specifit Growth Rate，SGR)逐渐与高密度组拉大差距，到135 d时，各组间差异显著(P＜0.05)，说明养殖密度对罗非鱼的生长性能产生显著影响。最高密度组(20.6 尾/m²)的成活率(Survival Rate,SR)显著低于其他各组(P＜0.05)，说明养殖密度过高导致成活率降低。饵料系数(Feed Conversion Rate，FCR)随着养殖密度的增加先降低后升高，各组间差异显著(P＜0.05)，当养殖密度为14.7 尾/m²时饵料系数最低，为1.63，说明适当增加养殖密度可以降低饵料系数。最高密度组(20.6 尾/m²)在养殖后期成活率下降,这是导致该密度组饵料系数升高的主要原因。总产量(Total Gross Production，TGP)随养殖密度的升高而升高，但因养殖密度在20.6 尾/m²时的成活率最低，使得总产量在14.7和20.6 尾/m²时相当,均为283.38 kg。氨氮和磷酸盐随养殖密度和养殖时间的增加而升高，使得养殖后期最高密度组(20.6 尾/m²)受到的胁迫增加，这也是养殖密度为20.6 尾/m²时在养殖后期罗非鱼成活率降低的主要原因之一。综上所述,提高养殖密度能在一定程度上增加养殖产量，但高密度带来的水质恶化及胁迫会导致罗非鱼成活率下降，因此建议在零换水条件下，体质量为(11.95±0.50) g/尾的罗非鱼的养殖密度为14.7 尾/m²。

Abstract:

In order to explore the most suitable density level for Oreochromis mossambicus culture to reach the market specifications under the condition of indoor zero water exchange,four density gradients were set up in this experiment,and the culture lasted for 135 d to study the effects of different culture densities on the growth performance of O.mossambicus in confined water and the water quality of aquaculture water.The results showed that with the increase of culture time,the Final Body Weight (FBW),Weight Gain Rate (WGR) and Specific Growth Rate (SGR) of the low-density group gradually widened the gap with the high-density group.And by 135 d,the difference between the groups was significant (P＜0.05),indicating that the culture density had a significant effect on the growth performance of O.mossambicus.The Survival Rate (SR) of the highest density group (20.6 ind./m²) was significantly lower than that of the other groups (P<0.05),indicating that the high culture density led to a decrease in survival rate.The Feed Conversion Rate(FCR)decreased and then increased with the increase of culture density,and the difference between groups was significant (P＜0.05).When the culture density was 14.7 ind./m²,the feed conversion rate was the lowest,which was 1.63,indicating that the appropriate increase of culture density could reduce the feed coefficient.The Total Gross Production (TGP) increased with the increase of culture density.However,due to the lowest survival rate when the culture density was 20.6 ind./m²,the total production was similar at 14.7 ind./m² and 20.6 ind./m²,both of which were 283.38 kg.Ammonia nitrogen and phosphate increased with the increase of culture density and culture time,which led to the increase of stress at the highest density group (20.6 ind./m²) in the later stage of culture,which was also one of the main reasons for the decrease of survival rate of O.mossambicus in the later stage of culture when the culture density was 20.6 ind./m².In summary,increasing the culture density can increase the culture production to a certain extent,but the deterioration of water quality and stress caused by high density will lead to a decrease in the survival rate of O.mossambicus.Therefore,it is recommended that the culture density of O.mossambicus with a mass of (11.95±0.50) g/ind. is 14.7 ind./m² under the condition of zero water exchange.