Social group during housing and testing modulates the effect of ethanol on zebrafish (Danio rerio) behavior

Zebrafish (Danio rerio) are a popular model organism in behavioral pharmacology research due to many genetic and neurological similarities with humans. As a social species, the presence (or absence) of conspecifics during housing and testing is likely to affect behavior, but these effects have not yet been well characterized. The goal of the current study was to better understand how social variables influence depth preference in zebrafish. Subjects were housed individually, in pairs, or in groups of four, then tested in a novel tank either individually or with their tankmates. Prior to testing, fish were exposed to 0.0%, 0.5%, or 1.0% ethanol. Behavior was recorded using a combination of manual coding methods and ANYMaze (™) video-tracking. Our results demonstrated more exploration by fish tested with their tankmates, and less exploration by fish tested in isolation. Additionally, the effects of ethanol on diving behavior were modulated by social groups during both housing and testing. We conclude that social variables likely contribute to the variability of behavior often observed in pharmacological research with zebrafish, and that additional effort should be directed to both standardization and further characterization of these variables.