Color Preference in Danio rerio: Effects of Age and Anxiolytic Treatments.

Zebrafish are increasingly used in neurobiological and behavioral studies. Possible stimuli to manipulate zebrafish behavior are being investigated. The presentation of colors appears to be one of the most used approaches, but there is much debate about the exact color preference. Here we have investigated the color preference in both larvae and adult zebrafish. We have studied the effects of wavelength, contrast, intensity, and location. Furthermore, we have tried to manipulate the preference with anxiolytic drugs (ethanol and buspirone). Our results show that both adults and larvae have a clear preference for blue zones while they avoid yellow-colored zones. Red and green zones have an intermediate preference. Part of the yellow aversion is caused by a fear for this color and can be diminished by the treatment with anxiolytic drugs. The location of the color appears to be of critical importance. Presentation of the color on the walls induces an approach response whereas presentation on the bottom induces an aversion. In conclusion, colors are important stimuli to manipulate zebrafish behavior and can be used in behavioral models. Standardization of the procedures and a clear description of the used methodologies are, however, essential.