Figure 2.

Zebrafish prefer to stay in close proximity of the stimulus tank that contains stimulus fish (US) throughout training (the 1^st [upper and lower bar graphs on the left] and the 20^th [upper and lower bar graphs on the right] trials are shown representing the first and last trial of training). The data are expressed as percent of time spent per unit of area of the tank. Mean ± S.E.M. are shown, sample sizes (n) equal 20 for both the paired and the not-paired training group. Random chance is indicated by the straight horizontal line. Note the strong preference shown towards the target zone (black bars) that contained the stimulus tank with the conspecific stimulus fish in both the paired training group (upper two graphs) and in the not-paired training group of fish (lower two graphs).