Figure 3: The effect of receiving physical stimulation on cortisol levels of the surgeonfish C. striatus.

Plasma cortisol levels of individual surgeonfish C. striatus that had access to mechanically moving cleaner fish models or to stationary models. Within each group, surgeonfish were either exposed to a confinement stress test (confined group—black bars) or remained unconfined (unconfined group—white bars). P-values refer to significant differences between fish with access to physical stimulation or no access (* two-way ANOVA, P<0.05). Error bars represent ± 1 s.e.m. Sample sizes (number of individual surgeonfish) are given in parentheses.