Fig 1.

Static positions of locomotor behaviors of male and female zebrafish recorded in control (A-C) and odor-stimulation conditions (D-F). The fish were separated by a net inserted in the middle of the container (indicated by bold dashed lines). Data were plotted in 15-sec intervals for a total of 15 min. Under control conditions (no odor stimulations), in pair-wise male-female setting, both the male and female fish show high sexuality levels, i.e., they displayed fast swimming behaviors and spent most of the time swimming close to the net in attempt to contact each other. In male-male or female-female settings, the fish randomly swam in the container, and they did not spend extra time swimming near the net. In response to odor stimulation, the behavior of the fish in the male-female setting remained unchanged. However, in the male-male setting, upon odor stimulation, the fish showed high sexuality levels. They increased the speed of swimming, and spent most of the time swimming close to the net in attempt to interact with each other. No obvious changes in swimming behaviors were seen in the female-female setting.