Collective Behaviour of Zebrafish

Recent years have seen the emergence of a new understanding of collective behavior in biological systems, and its connection/mapping with more familiar systems described by statistical mechanics. The field has been dominated by two systems - flocking birds (in particular Starlings) and swarming midges. So-called agent-based models hold promise for reproducing collective behavior in these systems, where the interactions are profoundly different. Birds interact topologically - with a fixed group of neighbors, while midges seem to interact over a certain distance regardless of the number of neighbours. The mapping of statistical mechanical concepts to these systems has yielding intriguing results, such as a (non-equilibrium) chemical potential for midges.

Spatial distribution of the nearest negibour of the zebrafish. Top: in a group of 50 fish. Bottom: in the case of 2 fish. Left: XY plane. Right: XZ plane.

However, nature is not limited to two systems, of course. Fish exhibit an entirely different scenario. For example, hydrodynamic coupling between individuals may have a profound effect upon the dynamics, yet remains almost completely unexplored in a biological system . We use zebrafish as a lab-based model system, and have carried out what we believe to be the first 3d tracking studies, which reveal structural and dynamical information, comparable to that obtained in colloids.

1. Yang Y, Turci F, Kague E, Hammond CL, Russo J and Royall CP, "Dominating Lengthscales of Zebrafish Collective Behaviour", PLOS Comp. Biol. 18 e1009394 (2022) link to PDF