Objective The bioflocs technology has been widely used in aquaculture, playing a role in water conservation and emission reduction. This technology is currently applied to artificial breeding of large yellow croaker (Larimichthys crocea). The study aims to discuss the effects of different carbon sources on the formation of bioflocs, water quality and seeding effects in the water of L. crocea fry cultivation.

Methods Glucose, sucrose, and brown sugar were used as carbon sources. Three experiment groups with a carbon-nitrogen ratio (C/N) of 15 and one control group without carbon sources were set up for L. crocea fry cultivation experiments.

Results The results showed that after 30 days of cultivation, the bioflocs volumn (BFV) and total suspende solide (TSS) values of each experiment group were significantly higher than those of the control group (P<0.01), while the BFV and TSS values of the brown sugar group were significantly higher than those of the glucose group and the sugar group. The crude proteins content of bioflocs in each experiment group was significantly higher than that in the control group (P<0.05), while the crude proteins content of bioflocs in the brown sugar group was significantly higher than that in the glucose group and the sugar group (P<0.05). The differences in ammonia nitrogen and nitrate content values among the experiment groups were not significant (P>0.05), but were significantly lower than those in the control group (P<0.01). The nitrite content values in each experiment group were significantly lower than those in the control group (P<0.01), and the nitrite content in the brown sugar group was significantly lower than that in the glucose group and the sugar group (P<0.05). The pH values of each experiment group were significantly lower than those of the control group (P<0.05), and the brown sugar group had the lowest pH value, which was significantly lower than the glucose group and the sugar group. The absolute growth rate and specific growth rate of L. crocea yellow croaker fry in each experiment group was significantly higher than that in the control group (P<0.05). The brown sugar group had the highest absolute growth rate of L. crocea fry, which was significantly higher than the glucose group and the sugar group (P<0.05). The survival rate of L. crocea fry in each experiment group was significantly higher than that in the control group (P<0.05), while the brown sugar group had the highest survival rate, which was significantly higher than the glucose group and sugar groups (P<0.05).

Conclusion The experimental findings revealed that all test groups successfully enhanced aquaculture water quality and efficiency, with brown sugar emerging as the most effective carbon source. The results of this study could provide a reference for optimizing the bioflocs breeding technology of L. crocea.