Fish groupings, also known as shoals, are collections of fish that swim together in a coordinated manner. Schools of fish are one type of fish grouping, where the fish swim in unison and often have a leader or dominant fish. Schools of fish can be found in both freshwater and saltwater habitats, and they are typically made up of the same species of fish. The size of a school of fish can range from just a few individuals to thousands. Fish groupings are beneficial for the fish, as they provide protection from predators and help the fish find food more easily.