Strength in numbers - why fish swim in schools

Fish swim in schools for several reasons:

Protection: Swimming in a group helps protect fish from predators. It's harder for a predator to single out one fish from a large, moving group. Also when fish are closely clustered together (especially smaller fish) it appears to be one large fish which can trick larger prey.
Foraging: Schools can be more efficient at finding food. When one fish finds a food source, the others can quickly join in.
Hydrodynamics: Swimming in a school can reduce the energy each fish needs to swim. The fish can take advantage of the water currents created by their neighbors.
Mating: Being in a school increases the chances of finding a mate, which is important for reproduction.
Navigation: Schools can help fish navigate through their environment more effectively, especially during migrations.

These benefits make schooling a successful strategy for many fish species.

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