The Effect of Disinfection Strategies on Transmission of Aeromonas salmonicida and Yersinia ruckeri in a Recirculating Aquaculture System

Continuous addition of Aeromonas salmonicida (which causes furunculosis) or Yersinia ruckeri (which causes enteric redmouth disease, or ERM) broth cultures to recirculating aquaculture systems, without fish, resulted in the presence of these pathogens in the fluidized sand biofilters.Disinfection of the recirculating systems, except biofilters, with 200 ppm sodium hypochlorite and flushing biofilters for 24 hours with filter-sterilized spring water (FSSW) did not prevent outbreaks of furunculosis or enteric redmouth disease after stocking Arctic char (Salvelinus alpinus) or rainbow trout (Oncorhynchus mykiss), respectively.Disinfection of the entire recirculating systems with 10 ppm Chloramine-T following outbreaks of furunculosis or ERM, or after addition of broth cultures prevented transmission of ERM in three trials and in two of three trials with furunculosis.Within 75 days of stocking Atlantic