There is increasing evidence that fish gain energetic benefits from the hydrodynamic
interactions when they swim in a school. The most recent indications of such benefits are a
lower tail (or fin) beat at the back of a school and reduced oxygen consumption in schooling
fish versus solitary ones. How such advantages may arise is poorly understood. Current
hydrodynamic theories concern either fish swimming side by side or in a diamond
configuration and they largely ignore effects of viscosity and interactions among wakes and …

In a computational model of hydrodynamics based on the Multiple Collision Dynamics
modelling technique, we investigate hydrodynamic advantages of fish swimming in an
infinite school. We show that the average Froude efficiency of individuals swimming in a
school is higher than of individuals swimming solitarily for each of four spatial configurations
(line, phalanx, rectangular and diamond-shaped). These benefits may emerge from several
kinds of interactions among wakes and individuals.