Fig. 2. Skin darkness of socially dominant and subordinate Arctic charr allowed to interact in pairs on a white (N=7) or black (N=7) background. Skin darkness was measured on a linear grey scale, where 0 is white and 255 is black, 24 h before (white bars) and after 5 days (black bars) of social interaction. Controls are fish that were visually isolated on the white (N=8) or black (N=8) background. Values are means + S.E.M. Means with no common superscript letters are significantly different (P<0.05; Sheffé post hoc test).