Shoaling preferences in female zebrafish and the effects of nonapeptides and environmental enrichment
Summary
To date, relatively few studies have addressed the mechanisms behind sociality or basic social grouping. Here, we attempted to address this empirical gap by examining the mechanisms underlying sociality in zebrafish. We investigated zebrafish shoaling preferences for groups of different sizes under different circumstances and found that zebrafish preferentially associated with larger groups of conspecifics over smaller groups. This was unaffected by social context or how stimulus shoals were presented: fixed on both tank ends, or in a way that simulated more natural shoal movement. Next, we investigated if zebrafish shoaling can be affected by nonapeptides of the isotocin/arginine vasotocin family, which have been shown to affect several social behaviour patterns in many other species. We demonstrated that vasotocin affected shoaling behaviour in zebrafish. Additionally, we investigated the effect of rearing environment – plain vs. enriched - on shoaling preferences and responses to a novel object. We found no significant effects of rearing environment on shoaling behaviour. Exploration of novel objects was also unaffected by rearing environment, though our results suggest that the novel object utilized did not induce novelty responses, compromising interpretation of this result. In conclusion, zebrafish shoaling preferences for larger groups over smaller ones appear to be relatively stable. Our results suggest a role of AVT in the regulation of zebrafish shoaling. Combined with other recent findings, this supports the hypothesis that nonapeptides may play an important role in the regulation of sociality across vertebrates.