封闭型水体中养殖密度对罗非鱼生长性能和水质的影响OA北大核心CSTPCD

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 re-sults 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),indi-cating that the high culture density led to a decrease in survival rate.The Feed Conversion Rate(FCR)de-creased and then increased with the increase of culture density,and the difference between groups was signifi-cant(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 To-tal Gross Production(TGP)increased with the increase of culture density.However,due to the lowest sur-vival 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,increas-ing 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.There-fore,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.