“…The AnAOB activity could be inhibited by the presence of oxygen ( Liu et al, 2016 ); so far, no anammox activity has been reported in pond aquaculture water. However, AnAOB can be detected in aerated systems, such as nitrogen-removing moving bed biofilters ( van Kessel et al, 2010 ; Persson et al, 2014 ), rotating biological contactor and biofilters ( Egli et al, 2003 ), and the simultaneous partial nitrification, anammox, and denitrification (SNAD) bioreactor ( Lu J. et al, 2020 ). They probably inhabit the oxygen-depleted zones of aerated biofilters ( Mulder et al, 1995 ), where an anoxic environment is created by AOA, AOB, and heterotrophic bacteria.…”