The light\/dark test is increasingly being adopted as one of the main behavioral assays in zebrafish neuroscience research. It is based on the innate preference of adult zebrafish for a black vs. a white compartment. Modifications and extensions of the protocol increased its breadth, but also its heterogeneity. The protocol presented here involves confining the animal in a central compartment for a initial 3-min acclimation period, followed by free exploration of an acryllic tank with a black and a white compartment. In addition to observing the spatial distribution of the animal, "ethological" variables (risk assessment, erratic swimming, freezing, thigmotaxis) are also manually scored in the white conpartment; these endpoints are selectively sensitive to drug treatments. The protocol is intended to measure anxiety-like behavior, with anxiogenic effects decreasing time on white and increasing risk assessment and thigmotaxis; some treatments also increase erratic swimming and freezing.