Housing Conditions Affect Adult Zebrafish (Danio rerio) Behavior but Not Their Physiological Status

Abstract

Zebrafish is a valuable model for neuroscience research, but the housing conditions to which it is exposed daily may be impairing its welfare status. The use of environmental enrichment and the refinement of methodology for cortisol measurement could reduce stress, improving its welfare and its suitability as an animal model used in stress research. Thus, this study aimed to evaluate (I) the influence of different housing conditions on zebrafish physiology and behavior, and (II) skin mucus potential for cortisol measurement in adult zebrafish. For this, AB zebrafish were raised under barren or enriched (PVC pipes and gravel image) environmental conditions. After 6 months, their behavior was assessed by different behavioral paradigms (shoaling, white-black box test, and novel tank). The physiological response was also evaluated through cortisol levels (whole-body homogenates and skin mucus) and brain oxidative stress markers. The results revealed that enriched-housed fish had an increased nearest neighbors’ distance and reduced activity. However, no effect on body length or stress biomarkers was observed; whole-body and skin mucus cortisol levels had the same profile between groups. In conclusion, this study highlights the skin mucus potential as a matrix for cortisol quantification, and how housing conditions could influence the data in future studies.

Direct Evidence for Using Coriandrum sativum var. microcarpum Essential Oil to Ameliorate Scopolamine-Induced Memory Impairment and Brain Oxidative Stress in the Zebrafish Model

“…The present study explored The novel tank diving test (NTT) examines how zebrafish respond to unfamiliar environments, causing them to initially spend more time at the bottom due to anxiety. However, as they become more familiar with the new setting, they gradually adjust and start exploring more at the top of the tank [36]. Thus, NTT evokes motivational/instinctual conflicts between the geotaxis behavior of diving to the bottom of the "protective" pool and the subsequent vertical exploration of the upper water column, targeting the phenotypic domains of exploration and locomotion [37].…”