Enhanced growth and decreased mortality in Atlantic salmon (Salmo salar) after probiotic bath

Aims Disease in farmed Atlantic salmon occurs in all its life stages. Salmon are particularly vulnerable to infectious diseases at transition from the freshwater stage to the saltwater stage. Our aim in these studies reported was to investigate the possibility that waterborne delivery of a probiotic comprised of naturally occurring marine bacterial species would reduce the mortality and improve the health and growth of farmed Atlantic salmon. Methods and results In three trials at two aquaculture production sites in Norway, isolates of Aliivibrio bacteria were added to the rearing water of Atlantic salmon. The fish were followed in 4–6 months after one single bath with observations and samplings. Growth, ulcers and survival were recorded. At the end of the studies growth was up to 31% larger in the probiotic enhanced groups and in trial 1 both mortality and prevalence of ulcer were significantly lower in the probiotic enhanced group compared to the control. Feed conversion rates were recorded in trial 1 and 2 and were from 9 to 28 % better for the probiotic enhanced groups compared to the control groups. Conclusion Bathing of Atlantic salmon with probiotic Aliivibrio strains increased growth, reduced mortality and improved FCR in the postsmolt period. Significance and Impact of the Study The study demonstrates the potential to enhance growth, prevent ulcers and decrease mortality in Atlantic salmon after adding probiotic strains of Aliivibrio spp. into the rearing water. The study can have impact on animal welfare, economy and sustainability in the aquaculture industry.