Effect of testosterone and fluoxetine on aggressive behaviors of fighting fish, Betta splendens

Effects of oral administration of testosterone and fluoxetine exposure on aggressive behavior of the fighting fish, Betta splendens, were investigated. Testosterone diluted in ethanol and sprayed on pre-weighted pellet to achieve concentrations of 0, 1, 2 and 4 mg/kg of hormone in food. Two main behaviors were recorded: the time in front of mirror and duration of the gill flaring using a mirror 8 and 15 days after the start of the experiment. Then, half of the specimens in each treatment subjected to waterborne fluoxetine at a concentration of 100 μg/L for 24 hours and the behavior was recorded. After 8 days of feeding, the time in front of mirror and duration of gill flaring were not significantly different between the treatments. Duration of the gill flaring increased significantly after 15 days; however there was no significant difference for the behavior in front of the mirror. Over time the aggressive behaviors were reduced significantly after fluoxetine exposure. This study indicated that fluoxetine in the aquatic environment alters the aggressive behaviors of the fighting fish.