Robotic zebrafish shows how fish brains use vision to swim in flowing water

A collaborative study by EPFL’s BioRobotics Lab and Duke University has demonstrated that visual cues alone enable larval zebrafish to maintain their position in flowing water. By combining realistic neural network models derived from live imaging of zebrafish brains with detailed simulations of visual processing, spinal connections, and swimming reflexes, the researchers successfully replicated the fish’s optomotor response—the automatic swimming behavior that counters water currents. This approach, which integrates brain circuits, body mechanics, and environmental factors, highlights the importance of studying brain function in the context of an animal’s physical form and natural surroundings, rather than in isolation. To validate their simulation, the team built an 80-centimeter robotic zebrafish larva equipped with cameras as eyes and motors for its tail, controlled by the same neural circuits as the simulation. When placed in a natural river environment, the robot was able to hold its position against the current, mirroring real zebrafish behavior. The study also uncovered that a small portion