Schools containing hundreds or thousands of nearly identical fish can confuse predators and make it difficult to single out and attack a particular one. Small fish in a dense school, moving in unison, may discourage a predator by appearing as a single, much larger creature. Schooling makes it easier for fish to find food. With many more eyes to search for food, more meals will be found. By working as a team, a school may be able to seize larger food items than any one fish could manage to capture.
Lookdowns are just one of the many fish species that form schools.
Schooling allows fishes to swim longer, travel through colder temperatures, and avoid predators more effectively than if they swam alone. 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.