Effects of Enrichment and Alcohol on Aggression of Betta splendens

Research has investigated the aggressive response in male Betta splendens (Shapiro & Jenson, 2009), but little research has looked at environmental factors that could affect this response. Since the aggressive response is territorial, we hypothesized that Betta fish habituated to an enriched environment would react more aggressively than fish habituated to a sparse one. Fish are argued to be an appropriate model for human alcohol related disorders (Luchiari et al., 2015). It is possible that the Betta’s aggressive response could serve as a reliable human model of aggression. Therefore, we also hypothesized that once exposed to alcohol, Betta fish would display more aggression than without alcohol exposure. To test these hypotheses, six male Betta fish served as subjects; three were habituated to enriched environments and three to non-enriched environments. First we investigated the aggressive responses of fish via the presentation of a mirror. Then, we investigated the effect of alcohol on aggressive behaviors of these fish. Researchers measured five aggressive behaviors: broadside, frontal display, approach, tail beating, and hierarchy. Specifically, Betta fish were dosed for two minutes in a solution of 0.5% alcohol and returned to their home environment for testing, which proceeded as in phase one. Results revealed that frontal displays, tail beatings, and hierarchy displays occurred significantly more often pre-alcohol exposure than following alcohol exposure) suggesting that alcohol reduced the aggressive behaviors of subjects. No differences in aggressive displays existed between enriched and non-enriched conditions. Since alcohol is a depressant, it is possible that the observed decrease in aggressive behavior was a result of overall decreased motor activity. Therefore, future research should investigate the possibility of a dose-dependent relationship in aggressive responding by Betta fish. Further, more research is needed to determine what types of environmental stimuli affect the behavior of Betta fish in the laboratory