Fig. 1

Schematic diagram of the recirculating system, and the sampled sites including post-UV disinfection water (1), tank water from six different tanks in which fish were introduced following collection of baseline samples, denoted by X (2), pre-particulate filter water (3), post-particulate filter water (4), the fluidized bed biofilter (FBB) (5), and carbon filter water (6) (A), and timeline showing the time-points (TP) at which samples were collected from each site, in quadruplicate (B)