Effects of Biological Flocs on Growth Performance of Cyprinus carpio var. Furui No. 2 and Aquaculture Water Quality

[Objectives] To study the effects of biological flocs on growth performance of Cyprinus carpio var. Furui No. 2 and aquaculture water quality. [Methods] The comparative experiment method was adopted. An experimental group and a control group were set up, with 3 replicates in each group. The experimental group used beet molasses as the carbon source which was added once a week. The breed, quantity, and specifications of stocked fish in each group were exactly the same. The experiment lasted for 60 d. Fish growth indicators were measured every 7 d. After one week of the experiment, ammonia nitrogen and nitrite were monitored once a week, and dissolved oxygen was monitored once a day. [Results] The survival rate of fish, the average weight of , the weight gain rate, and the specific growth rate of the experimental group were significantly higher than those of the control group (P < 0.05), and the feed conversion rate was significantly lower than that of the control group (P < 0.05). One week after adding the carbon source in the experimental group, the ammonia nitrogen was lower than the control group, and after three weeks it was significantly lower than the control group (P＜0.05); after adding the carbon source, the nitrite in the experimental group was lower than the control group, there was no significant difference in the first three weeks (P > 0.05), and there was a significant difference after three weeks (P < 0.05). The feed conversion rate of the experimental group was significantly lower than that of the control group (P < 0.05). [Conclusions] Adding a carbon source can significantly reduce ammonia nitrogen, nitrite and other toxic and harmful substances in the aquaculture water, promote the growth of aquaculture fish and increase the feed utilization rate.