Why do fish school?
Fish learn to swim together as young, first as pairs and then in larger and larger groups. You have probably seen that fish turns as quickly as a flock of birds, as this is an instinct from birth. Almost 80% of all fish species will swim together as pairs or in a group at some stage in their life.
There are four main reasons why fish swim in the schools. The first is to support the social functions where there is proven that fish shows less anxiety and has a lower heart rate when in a group. By schooling the fish creates a good bond between the individuals which leads to the following advantages.
The second reason is that as they swim and their tails sweep from side to side, they set up tiny whirlpools or vortices in the water which effectively reduce the friction for each of a fish’s neighbours. Less friction means less effort and energy is required to swim.
The third reason is to look for food, simply because the number of eyes looking for food increases dramatically. Schooling predators has a better chance on working together to separate a smaller group to pick off the prey.
Finally, the third and the most important reason is for protection. By grouping into a tight, group or pattern, the ﬁsh minimise their chance of being picked off by predators creating a visual disturbance. The swirling mass of the fish becomes confusing for the larger predators.
There is safety in numbers.
The picture above is taken on Bida Nok, where you can find large schools of yellow snappers.