INTRASPECIES AGGRESSION AND MONO-AMINE LEVELS IN RAINBOW-TROUT (SALMO-GAIRDNERI) FINGERLINGS

The dominance hierarchy was determined in 6 groups of rainbow trout fingerlings. The dominant fish in each group were compared to the same-sized submissive members with respect to whole brain monoamine levels. The dominant fish exhibited significantly lower levels of norepinephrine and higher levels of dopamine than the submissive members. The submissive fish most frequently attacked indicated a greater reduction in dopamine levels than those submissive fish which were rarely attacked. There were no differences in serotonin. These data were compared to the mammalian data concerned with catecholamines and aggression.