Organic rainbow trout – does the diet composition influence the fish health?

Summary

Rainbow trout (Oncorhynchus mykiss) is the dominant fish species in Danish aquaculture and the production is yearly about 40.000 tons. Freshwater accounts for about 75% of the production, while the remaining comes from seawater. During the last few years an organic fish production has been initiated and the rates of farmed organic fish are continuously increasing. Antibiotic treatment is only allowed a limited number of times during the entire life of an organic fish and if more treatments are needed the fish must be sold with the status of being conventionally raised. Thus it is a challenge to prevent disease outbreaks, e.g. by feeding with diets providing optimal health for the fish by strengthening their immune system or the composition of the gut microbiota.