characterization of bacterial communities and fish growth in biofloc-based tanks for rearing eastern catfish (silurus asotus) or japanese eel (anguilla japonica)

The present study investigated the effects of water temperature and culture duration on silurus asotus or anguilla japonica growth performance and bacterial community in a biofloc technology (bft)-based system. a temperature-dependent higher growth performance was observed in s. asotus or a. japonica with the highest growth rate at 30℃ culture temperature. in 25℃-bft tanks, the bacterial diversity achieved the highest value before rearing the fish, while the highest bacterial diversity was observed in 30℃-bft tanks after rearing eel or catfish. the bacterial communities were differentially clustered depending on the temperature, culture duration, and fish species. proteobacteria and bacteroidetes were the most dominant phyla and 45 predominant genera were identified. among the predominant genera, cetobacterium was the most abundant which accounts for 16-38% in the bft tanks of catfish with different water temperatures. nannocystis (22.3%), cetobacterium (10.2%), and bacillus (13.3%) were observed the most abundant in the 20℃, 25℃, or 30℃ maintained bft tanks of eel, respectively. notably, the correlation analysis demonstrated devosia abundance could affect catfish growth positively, while the flavobacterium abundance could affect eel growth negatively. additionally, exiguobacterium acetylicum sk4913 exhibited the most probiotic potential among the 27 isolates from all the bft tanks considering its multi-enzymatic activities. in summary, the culture temperature at the biofloc-preparation stage and fish growth stage should be maintained at 20℃ and 25-30℃, respectively.