A group of fish is commonly called a school. This term refers to a social grouping of fish that swim together in coordinated formations. Schools can vary in size from a few fish to thousands, depending on the species and environmental conditions. Fish school for several reasons, including protection from predators, increased foraging efficiency, and enhanced navigation. Some species, such as herring and sardines, are particularly known for their schooling behavior, which can create stunning visual displays in the water.