Why Do Fish Swim in Schools?

By Aurora

Photo source: Len Radin

According to an online article, research in the York Centre for Complex Systems Analysis discovered that fish organize themselves better when they feel under attack.  The more stressed the fish feel, the more they pay attention to each other’s movements.  They believe that the level of synchronization makes it harder for predators to pick out one individual.  In addition, in some cases scientists believe that fish do this to make the predator think that there aren’t hundreds of fish, but one giant fish that is generally larger than the predator itself.

The synchronization in a school of fish is very important.  Scientists recently studied how better synchronization can help improve the survival rate in these schools.  For example, if fish are able to swim in a specific pattern at the same rate and speed, they will have a better success rate when enemies seek to make prey out of them.  In addition, the fish now have an easier time finding food.  Now that they swim in a large group, they have a higher chance of finding food. This, therefore, aids them in their ultimate goal to survive and reproduce.

What is another survival benefit of fish swimming in large schools? Can more than one species of fish swim in the same school? Why or why not?

  • Sara

    Wow i never knew that the survival rate of these fish would increase just because they swim in large groups. I decided to look up some more information on the fish and discovered that fish also form large schools so that they know atleast some eggs will escape predators because of the large amounts of eggs fish produce.
    It actually does matter in some cases which species of fish swim in the same school. Certain types of loaches like clown and kuhli loaches must be kept in a school with fish from their kind. As for Tetras, Barbs, and Danios, it doesn’t matter which species it only matters that they be kept in a school.


  • Andrea

    Great post, Aurora. I found some more research on why fish swim in schools. I found that the fish use less energy when they swim close together because it reduces the friction between the fish and the water. The fish are also able to swim close together without bumping into each other. They’re able to sense when other fish change direction by using eyesight (their eyes on different sides of their head make this easier for them), hearing, and sense of smell. Fish also tend to stay in the school that they were born into. Some fish, like piranhas, will attack and kill a fish that’s trying to come into their school.


  • Taylor

    Really cool post Aurora! I have talked about this a lot with many people and always asked myself “why do birds travel in groups? why do fish travel in schools?” its always been a curiosity of mine, but now i know its because of synchronization, and of course for survival and reproduction. I personally think that most species of fish swim in schools, usually new borns. I was wondering if you, Ms. Baker, or any of my classmates could expand on how swimming in schools is an easier time to find food, because I figured that if there are more fish wouldn’t it be harder to find food?
    I researched if any other animals other than the common fish or bird travel in schools, and turns out that elephants travel in schools as well. For the same obvious reasons, survive and reproduce. If you want further information on that check out this website:
    Not only did it discuss elephants traveling in groups, it enlisted other useful facts about elephants.

  • Leyla

    Awesome post, Aurora! This truly is a unique way for fish to protect themselves. After researching this topic, I learned that there is variability between how long fish swim in schools. Whereas some of them only swim in schools right after they are born, some stay in schools for their entire lives. As for Taylor’s question, it is easier for fish to find food when they are traveling in schools because it is more likely for a large group of fish to spot food than it is for one or two of them to find some on their own.


  • Samm

    Great post Aurora! I did a little research and found out many cool facts that I never knew about fish and their schools. I learned that a school of fish could have as many as one million members, and usually, the members are of the same species. I was always curious about that, and my research clarified it for me. I also found out that fish swim in schools, not only for protection, but because they are family. For example: Piranhas swim in schools, even though they are very tough, and if a piranha from a different family tries to join that school, the other piranha will kill him.
    Did you know that 20% of the fish population do not swim in schools? I thought that all fish swim in schools, but it turns out that some fish, such as Clown fish or swim in solitude.


  • Cartland

    Nice post, Aurora! I also did some research after read your post.
    I find that some fish that swim in schools secrete a slime that helps fish in their school reduce the friction between their body and the water, making it easier for them to swim.I think it’s very interesting, then I know that fish are not born to swim, they also need to learn how to swim. There’s some fish that are better then others.
    Fish only swim in schools with fish of the same species. I guess it’s because that the different species have different color and size, so they can not do synchronization very well. And it doesn’t work when the different species go together.


  • Alice

    Great post Aurora! This is so fascinating! I did a little more research on schools of fish and found out that it has been discovered that schools of fish take on the same overall shape. According to a study performed by Andrew Brierly of the University of Saint Andrews in Scotland, it was observed that Antarctic krill fish maintained a constant surface area to volume ratio. Although the size and density of the group varied significantly, the shape of the swarm of the fish remained the same. To explain this discovery, reseachers used computer technology to come to a simple solution. The researchers tentatively came to the conclusion that the shape of the school of fish depends solely on the amount of oxegyn in the water, along with the fishes’ instict to remain protected from predators, as Aurora began to explain earlier.


    Below are some interesting photos of Schools of Fish:


  • Monica

    the schooling of fish is a great evolutionary advantage for the species. Not only is it able to find a mate in large crowds, but it is also harder for a predator to locate one single fish which it turn increasing a fish’s odds of survival. I find it interesting that a similar process occurs with human beings. when there is a large crowd, we all move in oone giant group when a group is scared or nervous. This way, it is harder to pick out a single person. Birds also travel incrowds


  • Dan

    Fish also swim in schools because they create a huge water current that helps eachother move. When fish create a wagging motion the create a displacement in water that allows the fish behind it to move a higher speed, these small currents are called vorticles. When the water around the fish is moving quickly it takes less energy for the fish itself to move. While traveling in a school fish can cover larger distances!


  • Nick

    Nice post Aurora! I agree there are multiple benefits for fish to travel in schools. A benefit for swimming in schools that i found in my research are that there is a better chance of surviving if a fish is more focused on a whole pack, then one specific fish.

    I think that a fish is unable to swim with a separate species, because a fish is commonly attracted for a favorable fish. If more then 1 species of fish is traveling in a pack that would attract more predators of different species.

    This link below explains my reasoning for swiming in a school

  • Emily

    This was truly fascinating, Aurora. Before researching more about the topic, I was trying to come up with another logical reason for why the fish swim in schools. I was thinking, similar to what you had mentioned, that the fish who swim alone are much much more vulnerable and more likely to get eaten by a predator, than a fish who is swimming among hundreds of other fish. It could also cause the predator to become overwhelmed at the number of fish and also become distracted by their sudden and rapid movements.
    When researching, I found that the schooling process goes unnoticed among young fish and they don’t even realize what is happening. It kind of comes quite naturally to them. They also use vision to be synchronized with the other fish, and they also have hair-like receptors that help them to move through the water. It is also beneficial for a fish to swim in a school because it makes it becomes easier to scare off a predator. Fish, like many other organisms, are genetically programmed to know that safety lies in numbers. I really loved this post, Aurora!

  • Molly

    Nice post Aurora! Just like the others have previously commented, fish swim in schools for ecological advantages as well as survival and reproduction advantages. According to an article posted about observations collected from researchers at Penn University, schooling is now considered a form of imprinting. As baby and young fish, they swim together in pairs or in very small groups. But, when the fish reach adulthood, they swim in larger groups called schools. The behavior is also innate because it is strictly based on the genes of the fish, and every individual of the same species “schools” in the same exact way. On the other hand, to answer Aurora’s second question, fish of different species do not school together. As others have stated, the advantages of schooling pertain to the specific species because there are predator advantages, energy reduction, and more mating opportunities only within that one species.

  • Gurk

    Good job Aurora! I find that very good for the fish’s to be kept in school, not only they can be kept away from predators, just like Monica said. Its no different from African wild dogs. African wild dogs run away from predators together because they know who to follow, instead for them looking around because they know when one runs they all run.
    here is the link.

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