Pavlovian Conditioning of Aggressive Behavior in Blue Gourami Fish (Trichogaster trichopterus ): Winners Become Winners and Losers Stay Losers

Previous research has shown that Pavlovian conditioning of aggressive behavior enhances the ability of male blue gourami fish ( Trichogaster trichopterus ) to defend their territories in signaled contests. The authors show that this competitive advantage has both short-term and long-term consequences for territorial males. Following an encounter that was signaled for some males but not for their opponents, each winner and loser was forced to defend its territory against a novel male in an unsignaled encounter 3 days later. Males for which the first contest was signaled not only were more likely to defeat their rivals than control males but, having won that encounter, they also were more likely to win a second contest than fish that had lost their first encounter. All losers lost their second contest. These results are discussed in light of well-documented neuroendocrinological changes associated with winning and losing aggressive contests in territorial males.