How do fish know if they’re swimming in the right school?

Published 26 September 2012. ABCScience

Dr Ashley Ward is a fish biologist at the University of Sydney. He was interviewed by Rachel Sullivan.

Almost 80 per cent of the more than 20,000 known fish species school at some point in the life cycle.

Schooling helps reduce the risk of being attacked by predators, and also makes swimming easier because the fish position themselves so they are able to slipstream in their neighbours’ wake.

Some species school only when they are vulnerable juveniles, others when they are older. They begin by swimming in pairs and then in larger and larger groups of the same species.

While fish have big eyes to help them find prey and keep track of each other up close, they rely on their chemosensory system to track other fish of the same species in the vastness of the ocean, says Dr Ashley Ward, a fish biologist at the University of Sydney.

“A fish can smell itself, and recognises others with the same smell,” says Ward, who studies the social behaviour of fish.”