Year of Award


Document Type


Degree Type

Doctor of Philosophy (PhD)

Degree Name

Experimental Psychology

Department or School/College

Department of Psychology

Committee Chair

Allen Szalda-Petree

Commitee Members

Daniel Denis, Nathan Insel, Yoonhee Jang, Jerry Robert Smith


aggression, betta fish, Betta splendens, environmental pollution, Fluoxetine, wastewater pollution


University of Montana


Chemical concentrations of antidepressants have increased over the years steadily building in surface waters globally. These drugs have had various impacts on the animals tested, such as impacts on movement, motivation, and reproduction. In order to further investigate the effects of the antidepressant fluoxetine, male Betta splendens were exposed to the drug. These fish are naturally aggressive for reproduction purposes and have easily observable aggressive responses to other male fish. These characteristics make them a good model for studying Fluoxetine’s impact on reproduction, motivation, and movement. Males in this study were primed with either a female or empty chamber prior to choice testing trials. Choice testing trials included ten daily trials, five with a mirror to study aggressive responding and another five that served as a timeout condition. Latency and aggressive responding were measured for each trial with video cameras used to record individual behavior. While no significant differences were found for the preference for the mirror vs timeout condition, the fluoxetine did have a significant impact on the fish latency and aggressive responding behavior. Results showed an increase in latency and decrease in aggression when the fish were exposed to the drug. These results show support for the hypothesis that Fluoxetine has an impact on motivation and movement in Betta splendens.



© Copyright 2020 Susan Marie Greene