This experiment showed that oxygen intake was definitely correlated with gill cover erection and dorsal fin spread. In the second test, a fight among two rivals was simulated and the oxygen intake of the expected winner and loser was in comparison. Metabolic rates were not various between winners and losers before and through the fight, but winners showed higher oxygen consumption in the night after the fight. These results are according to costs of show performance and with long lasting physiological penalties of successful or losing a fight. Aggr. Behav.