Schooling fish are groups of their kind that move together in tight groups called schools to avoid predators and find food sources. Schooling fish also form tight formations to make complex maneuvers such as turning and changing directions easier for predators to spot, including switching directions simultaneously and performing coordinated changes of direction as a group.
Researchers believe that fish use their sense organs such as the lateral line, sight and hearing to communicate and form schools. Researchers also think the close proximity of schooling fish reduces friction and saves energy by minimizing swimming costs. Schooling also has other advantages: when predators attack schools of fish it becomes hard for them to target an individual because the complex movement patterns of all the group makes targeting individuals difficult allowing schools to escape quickly from predatory attacks.
Metabolic measurements have demonstrated that fish living in schools use significantly less oxygen per tail beat than individuals. One theory for this reduction could be that school members share information about an approaching predator by sharing senses with one another; this may occur through pressure waves, particles and light rays altering, chemical signals being sent via scent particles or even electromagnetic fields surrounding the school.
Although fish schooling behavior can be beneficial to their wellbeing, it can also be potentially harmful. Therefore, aquarium owners must ensure their fish remain in pairs or larger groups that allow for plenty of forward and backward swimming space.