Aggression has long been studied and there are many different circumstances that can provoke aggressive behaviors in different species. Serotonin and the level of enrichment of the environment are two variables that can affect an individual’s level of aggression. The study examined how Betta fish aggression was impacted when exposed to a serotonin reuptake inhibitor and an enriched environment. The study did not find a significant change in aggression when Betta fish were exposed to environmental enrichment alone or environmental enrichment and SSRIs simultaneously. However, SSRIs alone did decrease aggressive behaviors. Therefore, this study did not find that SSRIs and environmental enrichment interacted to modulate aggression in Betta fish.