Figure 2.

Adult male zebrafish form stable social relationships, and behavior patterns diverge significantly as social relationships solidify. A, Social interactions are characterized by aggressive behaviors (attacks, top) performed predominantly by dominants and submissive behaviors (retreats, bottom) displayed mainly by subordinates. B₁, Social status affects swimming activity. Kernel heat-map estimation plot of swimming activity over a 1 min period of filming for dominants (red) and subordinates (blue) on day 14 after pairing (n = 12 dominants and 12 subordinates). B₂, Average swimming frequency of all animals plotted in B₁ over a 1 min period of observation on day 14 after pairing for paired animals and day 14 for group housed animals. The shaded area illustrates the variance in swimming frequency (SEM). C, Quantification of filmed swimming activity [distance traveled (in centimeters) per frame] for all animals tested during a 1 min period each day for a 14 d pairing period (n = 16 group housed, n = 12 for dominants and 12 subordinates). Video frames during which the animals were interacting were excluded from analysis. Total tracked distance was normalized by the number of remaining video frames. Day 0 marks observations of animals before they were paired (before pairing; arrow). A, B₂, and C plot the mean ± SEM.