Have you ever wondered how fish are able to detect the smallest of changes in water pressure or movement in water. Or how when in schools they are able to swim seemingly perfectly in sync. Well fish have this really cool thing called a lateral line. Which in a sense is an organ it uses as its eyes ears and other senses all combined into one. The development of the line system and the placement of its sensory receptors varies slightly depending on species and its natural habits and habitat. But by using their lateral line system a fish can pick up on subtle changes in the water. It can help it to detect things like water direction, prey, predators, depth and change in water pressure.
Something to think about when your next contemplating how best to target a particular species perhaps. (Photo source Britannica)