A fish school may achieve coordinated movement without each fish tracking a crowd of neighbours.
Researchers at CNRS and collaborating institutions placed a real rummy-nose tetra in a closed-loop virtual-reality environment alongside four simulated fish whose interaction rules could be controlled. Across experiments and simulations, the living fish behaved as though it primarily followed its single most influential neighbour, with that neighbour changing dynamically. The finding challenges models assuming simultaneous attention to several neighbours and demonstrates how a continuously changing network of simple local interactions can sustain collective motion.
https://phys.org/news/2026-10-fish-schools-sync-influential-neighbor.html
