“…The taxa within each domain are associated with an aerobic and heterotrophic lifestyle (Dupont et al, 2012; West et al, 2016) or ammonia oxidation (Konneke et al, 2005; Swan et al, 2014; Qin et al, 2016), respectively. In contrast, the water in the fish tanks, both weaning- and grow-out tanks, were dominated by the bacterial taxa Polaribacter , Leucothrix , members of Flavobacteriaceae , Oleispira , Colwellia , Marinomonas , Pseudoalteromonas , Tenacibaculum , Vibrio , Mor- itella , Fluviicola , and Psychromonas ; where cultivated memb- ers are generally described as organoheterotrophic, aerobic or facultative anaerobic, psychrophilic or mesophilic micro- organisms with origin from marine environments (Yakimov et al, 2003; O’Sullivan et al, 2005; Urakawa, 2014; Bernardet, 2015; Bland and Brock, 2015; Bowman and McMeekin, 2015; Deming and Junge, 2015; Farmer et al, 2015; Sanchez-Amat and Solano, 2015; Staley, 2015; Suzuki, 2015; The Editorial Board, 2015; Dahal and Kim, 2018). The differences in microbial community structures between intake water and fish tank water were probably due to effective UV treatment of the water that greatly reduced the bacterial load, followed by microbial succession in the fish tanks.…”