Translating rodent behavioral repertoire to zebrafish (Danio rerio): relevance for stress research

The current study provides a detailed description of the pattern of exploratory behaviors encountered in adult zebrafish when exposed to a novel/unfamiliar environment using the light/dark box and open field tests. We also document the impact of an acute stressor (restraint stress) given just prior the onset of behavioral testing. We report the following main findings: (1) zebrafish display anxiety-like behaviors including dark-avoidance (in light/dark box test) and thigmotaxis (in open field test), (2) upon exposure to a novel environment (first 2 min), zebrafish display place preference for the outer zone of the testing apparatus where they seek escape via the transparent wall, and exhibit high locomotor activity accompanied by high swimming speed, (3) thigmotaxis, behavioral hyperactivity, and swimming speed habituate (decrease) over time, (4) prior history of stress attenuates the natural tendency to engage in dark-avoidance behavior and thigmotaxis, reduces attempts to escape via the transparent wall, and greatly increased behavioral hyperactivity and swimming speed. Stress-induced patterns of behavior normalize to levels comparable to that of non-stressed controls by the end of the 5-min test session. Taken together, these findings suggest that novel environment can elicit anxiety-like behaviors in zebrafish such as dark-avoidance and thigmotaxis and the prior history of stress greatly affects patterns of exploration, defensive behaviors, and coping strategies in the light/dark box and open field tests. These findings are consistent with previous findings in rodents and support the usefulness of such behavioral paradigms in zebrafish.