Incorporating ventilatory activity into a novel tank test for evaluating drug effects on zebrafish

The effects of ethanol and caffeine exposure on zebrafish, Danio rerio, were investigated using a combination of measurements of behavioral and physiologic responses in a novel tank situation. Ventilation activity as a physiologic measure was measured remotely by monitoring ventilation-related bioelectric signals from freely moving zebrafish in the test tank. The directions of the behavioral responses, except for outer area preference, were substantially the same in both ethanol- and caffeine-treated fish and qualitatively indistinguishable, suggesting that relying solely on behavioral measures may lead to inappropriate interpretation of drug effects when depending on limited behavioral parameters. By incorporating ventilation activity-related physiologic measures into the quantification of drug effects in novel tank tests, more-accurate evaluations of differences in the effects of moderate doses of anxiolytic ethanol and anxiogenic caffeine were possible. Here, we propose that combining physiologic measures such as ventilation rate and its variability with behavioral measures makes it possible to characterize the effects of environmental challenges on zebrafish in a multi-dimensional and more-detailed manner.