Locomotion and habituation to novel experimental environments in a social fish species

Abstract

Abstract The response of animals to novel environments forms the basis of open field tests, an assay extensively used in the study of animal behaviour. However, to assess an animal’s routine behaviour or measure their response to novel environments, researchers must provide enough time for proper exploration and habituation. Unfortunately, no study has ever explicitly characterized the habituation process, except on isolated individuals, which represents an unusual situation for many social species. We analysed the movement characteristics and group-level dynamics of a shoaling fish species (Gambusia holbrooki) in an open-field arena for 1.5 h. We tested groups of 4 fish with varying sex ratios and found that behaviour changed over time with exploratory behaviour followed by a decreasing then plateauing trend, which only stabilised after 29 min. This movement pattern was consistent across all different sex ratios, however, female-skewed groups showed higher levels of activity during the first few minutes. Finally, median nearest neighbour distance was initially low before increasing and finally stabilising at around 9 min (with some exceptions) following the introduction of fish to the arena.