However, it is a physical fact that a swimming fish generates vortices in its wake, so it follows that individuals in a school swimming behind each other will encounter vortices from the propulsive wakes of preceding members. Experimental and theoretical studies have invoked flow refuging, vortex capture, wall effects and tip vortices toexplain the hydrodynamic benefit and energetic savings associated with schooling. For example, if fish in a school adopt a diamond formation , an
individual located behind and in between two preceding members can take advantage of the average reduced velocity associated with the thrust wakes of the two preceding members .