Fish adapt and dynamically avoid an approaching robotic fish across repeated exposures.

Biomimetic robots are innovative tools for guiding animal behavior by triggering avoidance responses that steer movement away from the robot. Potential applications include livestock management and environmental conservation, such as directing fish away from pollution and oil spills. While predator-like replicas have traditionally been used to provoke avoidance, less is known about how conspecific-like robotic platforms may elicit threat-like responses depending on their approach behavior. To address this gap, we programmed a conspecific-like robot to repeatedly approach live fish in a free-swimming setup, with varying approach speeds in each trial. Our results show that repeated exposure increased the likelihood of avoidance responses, indicating changes in behavioral reaction over time. In some instances, fish displayed threat-associated responses, including freezing and evasive maneuvers characterized by extreme turns and accelerations relative to baseline swimming. The initiation of these evasive events depended on both robot–fish distance and relative speed, suggesting that avoidance responses in this context are not determined by distance alone. Additionally, avoidance speed increased dynamically with both robot speed and proximity. These findings provide quantitative insights into how approach dynamics shape avoidance behavior toward a conspecific-like robot, informing future models of fish interactions and the design of robotic systems aimed at guiding fish movement through controlled aversive cues.