Trajectories of large schools of Hemigrammus rhodostomus swimming under varying illuminance

Illuminance-tuned collective motion in fish <br> We experimentally investigate the role of illumination on the collective dynamics of a large school (ca. 50 individuals) of Hemigrammus rhodostomus. The structure of the group, defined using two order parameters, is quantified while progressively altering the visual range of the fish through controlled cycles of ambient light intensity. We show that, at low light levels, the individuals within the group are unable to form a cohesive group, while at higher illuminance the degree of alignment of the school correlates with the light intensity. When increasing the illuminance, the school structure is successively characterized by a polarized state followed by a highly regular and stable rotational configuration (milling). Our study shows that vision is necessary to achieve cohesive collective motion for free swimming fish schools, while the short-range lateral line sensing is insufficient in this situation. The present experiment therefore provides new insights into the interaction mechanisms that govern the emergence and intensity of collective motion in biological systems. <br> ####### This repository is the data that support the finding presented in the paper by Baptiste Lafoux, Jeanne Moscatelli, Ramiro Godoy-Diana and Benjamin Thiria, "Illuminance-tuned collective motion in fish" (Comms. Bio., 2023). <br> The files are netCDF, each containing the related metadata. Experiment with continous light variation and controls with fixed light intensity are stored in two different zip folder. <br> Please contact me for further info (baptiste (dot) lafoux (at) espci (dot) fr) <br>