The longest shoal in the world is Barra del Indio (also known as Del Indio, Barra Indio) with a length of 220 km in South America.
The term shoal can mean a few different things. It can be a large group of fish, a stretch of shallow water, or a sandbank in a stretch of water that is visible at low tide.
Any group of fish that stay together for social reasons is shoaling. About one-quarter of fish species shoal all their lives, and about one-half shoal for part of their lives