When swimming in turbulence, fish know when to go with the flow

When fishes swim in turbulent environments, the bombardment of eddies forces them to utilize active postural control and alter their kinematics to overcome the higher drag force, which often results in a higher cost of transport. As a result, it is hypothesized that when swimming, fish may actively seek out regions of reduced turbulence to minimize energy expenditure. To investigate how fish respond to spatial heterogeneities in turbulence, we conducted experiments where a group of Giant Danios (Devario aequipinnaturs) swam in a flow tank equipped with a jet array system. This system provided the ability to systematically vary the turbulence intensity independent of the swimming speed. The turbulence characteristics were quantified using Particle Image Velocimetry (PIV) and the trajectories and kinematics of the fish were captured by high-resolution cameras. Statistics regarding the fish locations and navigation strategies will be presented. Furthermore, changes observed in the fish behavior with respect to the increasing turbulence intensity will also be discussed.