Do Fish Have Fears?

By Molly

Photo by Protographer23

Of course, every human has a phobia of some sort, or something that frightens them every time they see, hear, or think about it. Plus, most fears humans have are natural and are subconscious.  On the other hand, goldfish can be trained to be frightened of images or things around them. New research and studies have shown that fish can be conditioned to react a certain way to a stimulus through classical conditioning. The study has created a breakthrough in human phobia research and possible solutions to human fears.

In a previous post on this blog, “Teach a Goldfish New Tricks” by Jeremy, he researched a study observed on goldfish learning simple tricks. He talks about a father and son teaching their pet goldfish how to navigate simple obstacles by luring them through with food. The fish complete several tricks like swimming through a pipe, swimming under a bar and even pushing a miniature soccer ball into a small net. The goldfish learned how to do these tricks because they were conditioned to a reward. This form of conditioning is operant because through trial and error the goldfish learn how to complete tricks in order to receive a reward.

In an article posted recently about a study on goldfish, the fish learned how to become afraid of a certain stimulus by a conditioned result. In the study, conducted by Masayuki Yoshida and Ruriko Hirano, the scientists trained the experimental goldfish to become afraid of a green light. They associated this light with a mild electric shock, so when scientists exposed the fish to the green light their heart rate would immediately slow down, or in other words become scared. The study was done to test if phobias could be controlled or not, and as a result the scientists were able to create a stimulus that the goldfish feared.

After the fish were trained to react to the green light, scientists injected lidocaine (a type of anesthetic) into the goldfishes’ cerebellum before they showed the fish the light. When the green light was shown to the fish with lidocaine in their brains they showed no fear of the green light. Scientists concluded that with a small dosage of lidocaine, the fish would forget their phobia of the green light and react as though they had never been trained to fear it.

This study has proven to be quite important to scientific studies relating to human brain reactivity and behavior because this could advance new technologies that will rid humans of our phobias. Although humans will never inject lidocaine inside our brains, the study proves that there is possibility to train humans to overcome phobias and fears that have haunted us in the past.

Why does a goldfish’s heart rate slows down instead of quickening like a human’s heart rate? Is this a contributing factor to why goldfish were able to be conditioned to be afraid? Finally, was this study useful to scientific research and future studies?

  • Alice

    Great post Molly! After reading this post, I did a bit more research on phobias. As the goldfish in this experiment are trained to become afraid of the green light, humans can also be “trained” to become afraid of certain things. Conditioning children to become afraid, like the goldfish, can explain many of their human behaviors later on in life. On the other hand, according to recent research, children can also be “trained” to overcome their fears. According to a recent article, fifty-five percent of children who attended a one-session treatment were able to overcome their phobias. It is important for humans to overcome their phobias when they are still young because children who are not cured are at a great risk for having problems later on in their lives. Phobias are a constant problem among human beings, as well as other animals, as Molly suggested. With treatment sessions, humans can often be cured of their phobias, in addition to possible chemicals that may be invented in the future, similar to the chemicals used on the goldfish.

  • Emily

    Very interesting article, Molly! After reading your article, I was thinking about how I myself have many phobias and how it prevents me from doing some of the things that I’ve always wanted to do. As Alice mentioned, it is important for humans to overcome their fears while they are still young, so that they may have less problems and deterrents when they are adults. I did some more research about this particular experiment and found that the cerebellum is responsible for fear conditioning in mammals, but that the difference in species means that not all the results from the experiment could be the same for humans. It was interesting how the fish’s heart rate slowed down when scared, but human’s heart rates increase. I also did some more research to determine whether phobias can be genetic and I happened across a study about mice. The results were that mice who were extremely anxious and bred with other mice who were also anxious were more likely to generate lines of mice who were overtly fearful. However it was also discovered that many of people’s fears have to do with negative past experiences. Although I think that it would be advantageous to create a chemical that gets rid of people’s phobias, I also wonder if that could have a negative effect on people’s lives. Maybe people would be less cautious, and more likely to put themselves in harmful situations. Do you think that a treatment for phobias could be a good thing?

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  • dawood

    Interesting post molly. I did a little research and I found out that a the scientists who did this test were in Japan. I also found out, the reasons that scientists are testing all these anesthetics on goldfish is, because they want to find out if they can erase a human phobia, like being afraid of heights or bugs. the scientists haven’t tried these tests on humans yet (and I don’t think they will) but i don’t think that these anesthetics would work on humans. Compared to a goldfish, a humans brain is much more complicated, the method of injecting something into someone’s brain sounds horrible and the anesthetics might also damage the brain in some way (long term affects). I’m not sure about this, but if scientists actually do figure out how to erase human phobia (using this method or a different one), would it be able to be used in human warfare?? It actually seems like a pretty good idea.

  • Deirdre

    This was a great post Molly! I really liked how you related our classwork to a new situation, it has helped me understand the topic even better than before. In response to Emily’s post, I do not think that treatment for a phobia would be a good thing for humans. I have researched doctors medicating social phobias, like social anxiety disorder. Since there it’s hard for doctor’s to tell if a patient actually has a social phobia, or if the patient is just shy; doctor’s now think they could be over prescribing anxiety medicines that treat these “phobias”. Medicine used to overcome phobias are all classified to reduce anxiety and can lead to reckless behavior. Most of these medicines had negative symptoms like weight gain and decrease in sexual interest. Another way to overcome fears is to visit a therapist. Talking with a therapist can help eliminate the irrational thoughts when it comes to your phobia. In the case of social phobias, a therapist can help you overcome the thought that the person you are talking to will automatically think you don’t know what your talking about. Therapy had mixed results. Although it worked to an extent, people with social phobia who took therapy still found their lives less interesting then others. So, should phobias be treated with medicines that have bad side effects, or should they be treated through therapy that only works some of the time? Maybe phobias shouldn’t be treated in any way at all, but overcome through personal choice.


  • Leyla

    Interesting comment, Deirdre! I believe that in cases where social phobias actually prevent one from functioning properly they absolutely need to be treated. For example, I once knew someone who had a phobia of leaving his house, and therefore always stayed home out of necessity. The most effective way of treating social phobias is through a specific kind of therapy known as cognitive behavioral therapy. In this form of therapy, the therapist helps the patient identify the irrational thought process and replaces it with a more realistic notion. It teaches the patient to think, for example, “These people may not be looking at be, but at something behind me.” Psychologists have observed that it only takes about 16-24 sessions of this kind of therapy for patients to show significant improvement. However, in my research I learned that about 90% of people with social anxiety are misdiagnosed, even though 15 million Americans suffer from it each year. In addition, many of these people don’t turn to anyone for help because they think they are the only one suffering from it. Do you think that the media doesn’t discuss social anxiety and its dangers enough?


  • Cartland

    It’s really a good article! An interesting view Molly! For the question, I researched about the goldfish and the phobia. I knew that the location of radioactive sites in the brain in goldfish is different than others. so I guess it’s why that goldfish’s heart rate are different than human’s. In this case, goldfish’s cerebellum is really important. We can see that if scientists injected lidocainethe in goldfish’s cerebellum, they would be not afraid of the green light any more. So I guess the cerebellum of a goldfish control some kind of sense system in goldfish’s body. And I’m also happy about this research. Because it’s absolutely going to help the study of human disease. I’ve heard a story about a human child who was been raised by a wolf group. Although he was just eight years old, he could run as fast as an adult man. So that means that the human child can be trained to do something too. And also, for the phobia, maybe the scientist can find out that which part of our brain that control the sense of afraid, maybe it can change by some particular ways. Like a goldfish can be trained to be not afraid about something or change their sense by some medicine, I believe that human can do it too. It’s really a helpful research for the studies of phobia!


  • Jessica K.

    Great post, Molly! Like Deirde, I particularly like how you zoomed into the topic of our class discussion and did more research on fear. It’s quite interesting that phobias can be triggered in fish by associating negative consequences to minor things. If lidocaine can be used to treat phobias in fish, then perhaps it may have the same effect on humans. However, this drug has multiple side effects and precautions that people should be aware of. However, not all fear is negative and should be treated. Multiple sources state that fear can be beneficial because there are certain things and situations that people should be scared of. Without phobias or fear of any kind, people may often land themselves in dangerous situations and not even realize. People and animals as well need limitations and boundaries and without fear of any kind, they would have no control. Some fears, however, can be treated and are not beneficial at all. For example, I personally have “zoophobia,” which means the fear of all animals. This fear is both beneficial and harmful because although I know to stay away from dangerous creatures such as sharks and lions, this phobia gives me a fear of small animals such as puppies and cats, as well.


  • Eva

    Very nice post Molly! I was very interested in this article and I wanted to research a little more on phobias. Although fish phobias are very interesting, I was a little curious on stranger phobias in humans. Many people in the world have very strange phobias. For instance Clinophobia is the fear of going to bed, and in some cases, beds themselves. The people that suffer from this phobia seem to be aware that they should be calm when going to bed and that it is in fact very normal, but their anxiety level always rises quickly as soon as they see a bed. However, unlike many other phobias, this particular one causes another problem for the bearer, insomnia. Insomnia is a condition where people have trouble sleeping and find themselves not being able to sleep at all. Like Alice said, many children go to group sessions and work on trying to cure their phobias at a young age before it progresses to anything. With Clinophobia, its not as easily dealt with.
    Although this phobia is very different from other phobias, in particular fish phobias, it shows us just how dangerous some phobias can be. It also raises the question if all phobias are dealt with in the same way, no matter how serious they can be.

  • Nick

    Great post Molly! Very interesting! In the post you said that giving the fish a small dose of lidocaine makes them forget . Does this liquid harm the fish? I know from research that a human can forget many things by an electric shock,and they forget everything they know, is this the same with the fish? The link I am posting below is showing how the electric shock can cure memory loss. Do you know how electricity can change your memory?

  • James

    Very well thought out post Molly! You mention in your post that goldfish learn to be afraid of a stimulus. Therefore they will be doing the opposite of habituation. Habituation means to learn to avoid a certain stimulus. I had began to do some more research on the phobia. It says that there is something called Hypnotherapy. This helps you lose your fear. It also says that phobias of fish are mainly caused by detachment from something or someone. They can also use Energy Psychology to help cure fears and phobias. It is shown to be effective because it was tested on a relationship between a male and female. I hope to continue this conversation about cures of fish phobia.

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