Understanding Schooling Fish – Part I

Do you know why some fish are smarter than others? That’s because the former are always in schools!

Jokes aside. In underwater documentaries, you may have observed thousands of schooling fish swimming around reefs, turning, rising, and diving in magical unison, seemingly responding to an internal and natural rhythm known secretly only to them.

To recreate this beautiful dance-like synchronization in your aquarium, you need to understand the complex schooling riddle.

There are many reasons why fish travel in schools. Firstly, they are programmed by evolution to know that safety lies in numbers. Should a threatening predator approach them, their first line of defense lies in “blinding” the predator with their confusing flashes of silvery stripes. This makes it more difficult for the enemy to focus on a single fish.

Schools also seem to find food easier, and some fish schools practically take on the role of street gangs, patrolling their territory and keeping a watch out of trespassers.

How Schooling Fish Do What They Do

It’s magical how each fish seems to know exactly where their friends are going and at exactly what time.

Though most fish schools use their vision to some extent, nature has also equipped them with some help.

Fish have a system of hair-like receptors similar to that in the human inner ear, and can sense water displacement with it. These tightly packed bundles of protruding hair are encased in a jelly-like sheath, and are scattered around the head and body. Most are concentrated in two canals running along the sides of the fish from the head to the base of the tail.

With the slightest change in pressure, these tiny hairs bend, and the fish quickly sense any unusual movement about it and responds accordingly.

How Schooling Fish Behave In Pairs

Deemed the safest spot, the center of the school is where most of the fish want to be. You may witness them vying for that spot by chasing and nipping at each other, though you shouldn’t worry too much about.

If a pair of schooling fish are kept in a tank, one of them will eventually begin to dominate and nip at its companion’s fins. It may also bully it mercilessly to the point of exhaustion.

To seek shelter and relief, the weaker fish is often forced to take cover and hide, especially during feeding times. After a short period of such torment, the weaker fish may succumb to stress and disease, and eventually die.

Given that it’s in their nature to school, having just on schooling fish will not solve the problem. Being a sociable creature, the lone ranger may feel lonely, and keep to itself in a corner most of the time as a result. It may also turn terrorist, biting and snipping at its other tank mates and damaging their fins.

How To Keep Schooling Fish Happy

Therefore, the solution is in getting the numbers right schooling fish tend to behave much better when they are in a group of at least six. Depending on your tank size, you may want to consider getting a dozen or so, or two different schools for a more spectacular display of color and motion.

In the next article, we will cover the subjects on feeding and breeding tropical schooling fish.

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