Mean relative gene expression results ± SEM. Mean relative gene (gldK (A), gldL (B), gldM (C), gldN (D), (sprE) (E), sprT (F), and porV (G)) expression results ± SEM in planktonic and biofilm cells of the low (LV) virulent F. columnare isolate following supplementation with a low (50 µg/L) or high (500 µg/L) cortisol dose. Only statistically significant differences are presented. The error bars indicate the standard error means and the asterisks indicate significantly different results compared to the non-supplemented controls. Significance levels are indicated on the graphs *, 0.01 ≤ P < 0.05; **, 0.001 ≤ P < 0.01.