How and Why Do Fish School?

schooling fish

Schooling Fish by: Wikimedia Commons Eric Kilby

How and why do fish school? First off, an aggregation of fish is when a bunch of fishes are together. Shoaling is when a group of fish come together for social reasons. It is more specifically called schooling when the fish also move together in coordination. Half of all fishes shoal at one point during their lives, and one quarter of fishes shoal their whole lives.

There are a multitude of reasons why fish school. These include safety in numbers , easier to find food, swimming more efficiently and easier to find potential mates. Schooling behavior confuses potential predators, which cannot focus just on one fish to catch.

Schooling takes coordination, as each fish senses its position in relation to the other fishes. All fish have a lateral line around their bodies that help. There are tiny holes with sensitive hairs in them in the lateral line.

Most fishes don’t school when it is dark, so they are dependent on their eyesight.

According to some scientists, how they school is dependent on their genes. It’s not a learned behavior. Scientists did experiments on some small fish (see here for details) and cross bred individuals that preferred schooling to those that didn’t. The results told the scientists that there are parts of the fishes’ genome associated with schooling.

Another mystery is how fish somehow know when they are with fish that look like themselves so they can school together. They don’t recognize themselves in a mirror like more intelligent animals, so how do they do it? An odd fish out in a school increases its chances that it’ll be seen by a predator.

They may use their senses: sight, smell (pheromones), and sound. But otherwise a Google search only comes up with conjectures.

What questions do you have about fish? I’ll cover them in future posts.

I consulted the following
Wikipedia article on Shoaling and Schooling Fish

This entry was posted in Fish. Bookmark the permalink.