The relative susceptibility of fish to infections by Flexibacter columnaris and Flexibacter maritimus

The susceptibility of freshwater and marine fish to infection by Flexibacter columnaris and Flexibacter maritimus was assessed in laboratory based experiments. Flexibactor columnaris produced a more severe disease in barramundi compared to goldfish. Both species suffered greater mortality at 25°C than at 20°C. Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) had similar levels of susceptibility to F. maritimus infection in seawater with approximate LC50 values of 2.3 × 105 and 1.6 × 106 CFU mL-1 respectively. However, at salinity of 15‰ greenback flounder (Rhombosolea tapirina) were more resistant to F. maritimus than Atlantic salmon.