The effect of social stress on the Standard Metabolic Rate (SMR) of brown trout, Salmo trutta

The effect of social stress, induced by confinement in pairs, on the SMR of the brown trout, Salmo trutta (L.), was investigated. Fish were confined in pairs under laboratory conditions and allowed to establish social hierarchies, with one fish becoming dominant and the other subordinate. The change in SMR of the subordinate fish was significantly greater than that of their respective dominant. Also, the more aggressive the dominant behaved towards the subordinate with which it was paired, the greater the increase in the SMR of the subordinate fish appeared to be. It is concluded that social stress causes an increase in SMR in subordinate fish and therefore imposes a metabolic disadvantage.