Why Do Fish Swim in Schools or Shoals?
Some fish swim alone; others stay in groups known as “schools” or “shoals”. A school of fish swims in formation, moving and turning with great precision. Schooling allows fishes to swim longer, and travel through colder temperatures.
The old saying that there is safety in numbers can be observed here. Not only are many eyes better than one in watching for enemies, but when threatened, a school of fish scatters in all directions.
Since the predator must choose which fish to pursue, usually only one fish is likely to be caught–a small price to pay for the survival of the group, schooling also insures reproduction and eases the task of food gathering.
Small fish in a dense school, moving in unison, may discourage a predator by appearing as a single, much larger creature.
Another benefit of schooling is that it brings the sexes together and increases the odds of successful reproduction. Many fish species form schools only when it is time to mate.
Schooling also increases the efficiency of swimming for fish. Drafting in the wake of their schoolmates allows fish to conserve energy, swim longer and even consume less oxygen than they would if swimming alone.