Large groups of mosquitofish can move together with little physical contact between individuals. This is because the individual fish coordinate their acceleration and deceleration. The fish accelerate toward a neighbor that is far away from or behind them, and decelerate when a neighbor is directly in front of them.Edit Summary
“We identify three key rules for the social interactions of mosquitofish (Gambusia holbrooki): (i) Attraction forces are important in maintaining group cohesion, while we find only weak evidence that fish align with their neighbor’s orientation; (ii) repulsion is mediated principally by changes in speed; (iii) although the positions and directions of all shoal members are highly correlated, individuals only respond to their single nearest neighbor” (Herbert-Read et al. 2011:18731).
“Fish responded to the position of their neighbors through short-range repulsion and longer-range attraction rules…mosquitofish actively changed their speed in order to avoid or move toward neighbors…Perhaps the most surprising finding of our study is the extent to which the single nearest neighbor dominates social interactions…we find that the turning angle of a focal fish is as correlated with its second and third neighbors as it is with its first, suggesting multiple interacting neighbors” (Herbert-Read et al. 2011:18734).