Let the fish decide! How group size, gender and dominance affect preference for environmental enrichment in zebrafish

摘要

Environmental enrichment often improves the welfare of captive animals yet is rarely applied to laboratory fish (Fig. 1). Wild zebrafish habitat features range of substrates such as silt, sand and gravel and both overhanging non-aquatic and rooted aquatic vegetation. Studies investigating enrichments compatible with toxicology requirements (such as glass or plastic rods) found little or no welfare benefits. Our study uses preference testing, letting the animals choose from a range of largely naturalistic designs rather than imposing objects selected for their hygienic qualities. By applying the enrichment preference assay to two distinct social contexts this study also aims to evaluate how group sizes affects the fishes' capacity to exhibit preferences.