Changes in attraction and repulsion indicators, depending on the species and the group size, were explored under controlled conditions. Two species, displaying different schooling behaviours in the wild were observed: the bigeye scad Selar crumenophthalmus and the barred flagtail Kuhlia mugil . In the bigeye scad, the polarity and speed were high and stable, and the nearest neighbour distance ( D NN ) decreased when the group...