UCSD - University of California - San Diego

08/26/2026 | Press release | Distributed by Public on 08/26/2026 10:27

Rules of the School

Published Date

August 26, 2026

Article Content

Key Takeaways

  • Scientists have developed a new understanding of how fish interact as they school in groups
  • The glassfish Danionella, an emerging model species in neuroscience, were found to copy their neighbors to align their movements within schools
  • Discovering this social copying rule opens a door to examining how the brains of many individuals interact to produce group-level collective behavior

For centuries, scientists have been fascinated by the remarkable coordinated movements of flocking birds, swarming insects and schooling fish.

Researchers have studied these natural phenomena in order to understand the rules of interactions between individuals that can produce complex group-level behavior. A collaboration of physicists and neurobiologists at the University of California San Diego has been studying schools of micro glassfish (Danionella cerebrum) to understand how the interactive mental processes of individual fish produce group-level decisions.

Their new paper, published in Physical Review Letters, dives into these questions and provides a new understanding of how individual fish use their perception of their neighbors' movements to copy those actions, leading to schooling behavior in groups. The research was led by Palka Puri, a recent graduate of UC San Diego's Physics PhD program, with Associate Professor Johnatan Aljadeff and Assistant Professor Matthew Lovett-Barron, both faculty in UC San Diego's School of Biological Sciences.

Puri's work provides a detailed, turn-by-turn account of the schooling behavior of micro glassfish across a range of developmental stages. Based on the computational model developed and investigated in the paper, scientists can now interpret the actions of individual fish and predict the dynamics of schools forming and breaking. The findings also open a door to understand how collective movement - a complex social behavior - emerges from sensory and motor processing in the brain of each fish.

Related content

An Emerging Model Organism

The Howard Hughes Medical Institute recently announced a new research effort into the neural mechanisms underlying complex behavior of the glassfish Danionella (recently featured in NPR and Science Magazine), described as a once-obscure fish now taking center stage as a model research organism. Future research on the physics and neuroscience of collective movements will greatly benefit from the combination of tractable mathematical models and empirical studies of glassfish collective behavior.

Social interaction rules: In previously accepted "classical" research, scientists predicted that fish align to the average direction of fish in their neighborhood (orange, left). Puri et al. report that glassfish instead copy one single neighbor at a time (blue, right).

The computational model described in this new paper overcomes prior limitations in the study of animal collectives. While physicists have long investigated collective behavior with models of active matter, it has been challenging to connect these models to the macroscopic movement patterns of animal groups in nature. By examining the movements of fish across group sizes, UC San Diego researchers discovered that individual fish "copy" the movement direction of a randomly-chosen nearby neighbor. This model can explain how schooling emerges during development, as the authors have previously shown. This pair-wise interaction leads to highly dynamic behavior in groups, which is fundamentally different from predictions of a classical model, in which fish align with the average direction of their neighbors.

The authors then went further, testing whether their models can predict the behavior of real glassfish by studying their interactions with "virtual fish" swimming in a virtual reality environment. When the authors programmed virtual fish to change directions, the real glassfish behaved according to the predictions of the pair-wise copying model.

Precise moments for pairwise copying in schools: Fish movement is segmented into alternating bursts (acceleration, turning) and glides (deceleration, linear motion). The coordination between bursts and glides of neighboring fish provides information on the timing and "intent" of each turn.

The authors also identified specific moments when fish implement the interactions defined by the model. The end of one fish's turn opens a "window of opportunity" for its neighbors to align with them. The researchers discovered that mature glassfish generate copying turns with fast reaction times, allowing for insight into the constant give-and-take of social interactions.

These breakthroughs will enable further investigations into the mechanisms of group movement, where Aljadeff and Lovett-Barron seek to understand the neurobiology of social copying in schools.

"Identification of these precisely timed social interactions, together with improved technologies for brain-wide neural imaging, will advance our understanding of how processing in the brains of individuals supports collective behavior," said Aljadeff, a faculty member in the Department of Neurobiology.

"The findings in this paper open exciting new opportunities for understanding how the brains of these fish pay attention to each other and copy each other's actions," said Lovett-Barron, also with the Department of Neurobiology. "Each fish is sensing and responding to their social partner's actions at discrete moments in time, and performing a specific mental computation. Since we can record across the brains of these transparent Danionella fish, we can start to uncover how their tiny brains achieve this. We hope to ultimately understand how complex collective behaviors like schooling emerge from the brains of many interacting animals."

The authors contributing to the study were: Palka Puri, Geoff T. Meyerhof, Julia L. Napoli, David Zada, Matthew Lovett-Barron and Johnatan Aljadeff.

The research was supported by Department of Energy grant DE-SC0022042, National Institutes of Health grants F31NS141340, DP2EY036251, and R01NS135853. Lovett-Barron acknowledges funding from the Searle Scholars Award, Sloan Research Fellowship, Packard Foundation Fellowship, Pew Biomedical Scholar Award, Klingenstein-Simons Fellowship in Neuroscience and McKnight Scholars Award.

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