Signaling on Prozac: altered audience effects on male-male interactions after fluoxetine exposure in Siamese fighting fish

Abstract

Selective serotonin reuptake inhibitors, such as fluoxetine, within the aquatic environment may adversely affect the health and behavior of exposed organisms. Most studies on the effects of inadvertent pharmaceutical exposure focus on the individual level rather than examining behavior within a network of individuals. Within communication networks, interactants send signals to multiple individuals, potentially altering, and being altered by, the behavior of nearby individuals. To address if fluoxetine interferes with communication within a network, male Siamese fighting fish interacted under three audience types (male, female, or no audience) and two exposure conditions (control, fluoxetine). In the control group, findings were similar to prior studies, with males altering gill flaring rate depending on the sex of the audience present. In the exposed group, gill flaring did not differ based on audience type and was lower overall compared to the control, suggesting a reduction in aggression. In contrast, both unexposed and exposed males performed more tail beats when a female audience was present, suggesting that fluoxetine has a context-specific effect on behavior. Behavioral changes during current interactions may affect behavior during later interactions as well as the outcome of future encounters with audience individuals. The influence of fluoxetine on total behavior within an interaction and loss of audience effect suggests it may generate broader changes in communication beyond the exposed individual, causing fitness consequences. This study stresses the importance of studying the effects of inadvertent pharmaceutical exposure on behavior in multiple social contexts to better understand its impacts on complex communication systems.