Schools of fish and flocks of birds display an impressive variety of collective movement patterns that emerge from local interactions among group members. These collective phenomena raise a variety of questions about the interactions rules that govern the coordination of individuals’ motions and the emergence of large-scale patterns. While numerous models have been proposed, there is still a strong need for detailed experimental studies to foster the biological understanding of such collective motion phenomena. I will first describe the methods that we developed in the recent years to characterize social interactions between individuals involved in the coordination of swimming in groups of Rummy-nose tetra (Hemigrammus rhodostomus) from data gathered at the individual scale. This species of tropical fish performs burst-and-coast swimming behavior that consists of sudden heading changes combined with brief accelerations followed by quasi-passive, straight decelerations. Our results show that both attraction and alignment behaviors control the reaction of fish to a neighbor. Then I will present how these results can be used to build a model of spontaneous burst-and-coast swimming and social interactions of fish, with all parameters being estimated or directly measured from experiments. This model shows that the simple addition of the pairwise interactions with two neighbors quantitatively reproduces the collective behavior observed in groups of fish. Increasing the number of interacting neighbors does not significantly improve the simulation results. Remarkably, and even without confinement, we find that groups remain cohesive and polarized when each fish interacts with only one of its neighbors: the one that has the strongest contribution to the heading variation of the focal fish, dubbed as the “most influential neighbor". Overall, our results suggest that fish avoid information overload when they move in large groups since individuals only have to acquire a minimal amount of information about the behavior of their neighbors for coordinating their movements.