About one-quarter of all fish species "shoal" and/or "school" for their entire lives, while about half gather in shoals or schools for limited periods. Any group of fish that stay together for social reasons are shoaling, and if the group is swimming in the same direction in a coordinated manner, they are schooling. When swimming in shoals, fish do behave somewhat independently, but they also relate to one another. Shoals of fish can be made up of mixed sizes of a single species or have mixed subspecies. Schooling fish are usually of the same species and the same age and size. Fish schools move with the individual members precisely spaced from each other. The main reason why fish school is for protection. By grouping into a tight, regimented pattern, the fish appear to blend together, confusing would-be predators.

_Franco Banfi is an award-winning underwater photographer and photojournalist who makes his home in the southern part of Switzerland, in a village close to Lugano Lake. To see more of his work, visit banfi.chi. _