Behaviour 2019
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Video stimuli elicit hormonal responses in Betta splendens fighters and bystanders
Ellen S. Davis, Wytney M. Schilt, Morgan J. Fons, Clara L. Madley, Kallie Fowler. UW-Whitewater, Whitewater, Wisconsin, United States

The ways in which social experience can modulate physiology and behavior are both myriad and widespread among taxa. Many of these aggression-related phenomena in particular have been well studied in male Siamese fighting fish, Betta splendens, although some obvious holes remain, including the role of androgens in these phenomena. We studied changes in androgen levels (11-Ketotestosterone, 11KT) in two situations: (1) following a fight with another male (Challenge effect); and (2) after simply watching two other males fighting (Bystander effect). We also investigated the effectiveness of video playback as a stimulus. For the Challenge experiment, we presented males with another male, a mirror or video of another male. For the Bystander experiment, males either watched two live males interacting or video of two males interacting. We found that 11KT increased significantly, whether males were involved in the fight or just watched a fight. Moreover, we found that both mirror and video playback are effective at eliciting these hormonal responses. The use of video stimuli in particular both allows for greater experimental control and reduces the number of animals required for research.