We report on the dynamics of collective alignment in groups of the cichlid fish Etroplus suratensis. Focusing on small- to intermediate-sized groups (10 ≲ N ≲ 100), we demonstrate that schooling (highly polarized and coherent motion) is noise induced, arising from the intrinsic stochasticity associated with finite numbers of interacting fish. The fewer the fish, the greater the (multiplicative) noise and therefore the greater the likelihood of alignment. Such rare empirical evidence tightly constrains the possible underlying interactions that govern fish alignment, suggesting that E. suratensis either spontaneously change their direction or copy the direction of another fish, without any local averaging (the otherwise canonical mechanism of collective alignment). Our study therefore highlights the importance of stochasticity in behavioural inference. Furthermore, rather than simply obscuring otherwise deterministic dynamics, noise can be fundamental to the characterization of emergent collective behaviours.

我们报告了慈鲷鱼Etroplus suratensis群体中集体排列的动态。专注于中小型群体（10  ≲  N  ≲  100），我们证明了学校教育（高度极化和连贯运动）是由与有限数量的相互作用鱼相关的内在随机性引起的噪声引起的。鱼越少，（乘法）噪声就越大，因此对齐的可能性就越大。这种罕见的经验证据严格限制了控制鱼类排列的可能的潜在相互作用，这表明E. suratensis要么自发地改变它们的方向，要么复制另一条鱼的方向，没有任何局部平均（集体对齐的其他规范机制）。因此，我们的研究强调了随机性在行为推理中的重要性。此外，噪声不仅可以简单地掩盖其他确定性的动态，还可以成为表征新兴集体行为的基础。