Do Fish Have Brains? Do They Have Feelings too?

By Nadine Oraby | 2020 Update

It has been theoretically proven that humans evolved from waterborne creatures. Naturally, this fact raises a question about their intelligence.

So, do fish have brains? And do they have feelings too? The clear-cut answer is yes, they have both, even if they are not as developed as those in human beings. Fish are highly intuitive and perceptive creatures that have fascinated biologists for years.

By reading this article further, you will understand approximately how a fish’s mind perceives things if the intelligence varies with species, and how much they can feel.

The Physical Brain of a Fish

Fish brains are very different from mammalian brains, so their physical outlook and mechanics are different as well.

You can judge by the size of the average fish head that their brains are quite small.

Small brains leave little room for development and therefore are not exactly known for processing complex thought and emotion.

However, larger fish like sharks have larger brains. Even so, shark brains are nowhere as close to mammalian brains.

The octopus is perhaps one of the most intelligent creatures you can find under the sea.

An octopus’s mind is greatly developed and helps it to perceive its surroundings.

Structurally speaking, the fish’s brain has a well-developed cerebellum. The cerebellum is the part of the brain that helps with involuntary motor function.

The fish also have a cerebrum since they are vertebrae.

Like all other vertebrae, the fish uses these parts of their brain to understand their environment, act on stimuli, and keep involuntary body functions running smoothly.

How Smart is a Fish? (Video)

How Developed is the Brain of a Fish?

Fish are not capable of complex thought processes.

They don’t even hold the same capacity of getting attached to their owners as mammals do, which is why people are so afraid of larger fish like sharks.

They are not capable of thinking, so they will attack anything that resembles their food.

Mammals that live in the sea like dolphins, on the other hand, are considered to be friendly and can bond with human beings and other species because of how complex their brain is in comparison.

This difference in development arises because:

The cerebrum of a fish brain is very simplistic and imparts a small amount of intelligence and voluntary action.

The cerebrum in mammals is more capable of voluntary thoughts and actions.

Mostly, the cerebrum of a fish helps to perceive a situation, and the cerebellum helps the fish to act on it; this is because the cerebrum also helps identify odors, sight, and sound.

This shows that fish usually act on intuitions and basic sensory stimuli rather than have a complex thought process.

How do Human Brains and Fish Brains Differ?

There are many differences between human and fish brains.

There are hundreds of physical differences between the brains of humans and fish, and this is why all of the other differences arise as well.

The most prominent difference we see is that of intelligence. Humans are highly intelligent creatures, and they can mold their environment to be more suitable to their needs.

Human beings have spent thousands of years evolving and shaping civilization into what we know today, even if a lot of it has been destructive!

All of these changes have come about as a result of the human brain.

Fish, on the other hand, have adapted to their environment over all these years. They have mainly evolved through natural selection.

They do not have the mental capacity to change their environment the way humans have completely.

How Intelligent Exactly is Fish?

Just because fish do not hold the same level of intelligence that human beings do, does not mean that fish are not intelligent creatures by themselves.

Here is a list of commendable intelligent features that nearly all fish exhibit:

Learning Capacity

Most fish have a good memory, which makes us see how amazing their learning capacity is as well.

This fact certainly debunks the myth that goldfish memory lasts for thirty seconds only!

In fact, an experiment with goldfish and a colored feeding tube showed that the goldfish remembered the color of the feeding tube one whole year after the experiment was conducted!

Goldfish have also seen to have a memory span of three months, and it is easy to teach them associated behaviors or “tricks” as well.

So much for having the memory of a goldfish!

Other fish are also seen learning a large number of associative behaviors.

For example, rainbow trout is seen associating the presence of a bar with the availability of food, and they remembered this association eight whole months after the experiment ended as well.

Spatial Recognition

Fish also recognize their surroundings and have a good sense of time as well.

If you have ever kept fish in a tank at your home, you have probably seen this for yourself.

You must have a time where you feed your fish every day, and probably a certain spot on the tank where you pour in the food.

After continuing this habit for a long time, you will begin to notice that the fish begin to gather on that spot every single day at the same time in anticipation of food.

This has also been seen in fish that live in the sea as well.

They sleep at a particular time, and have a particular time to wake up, they are aware of their home as well and the areas where they can find food for themselves.

This is how we can tell that fish have a good idea of their surroundings as well.

Making Shelter

Many fish have learned to shelter themselves in the vastness of the sea.

It is often seen as mutualism or commensalism. An example is that of the clownfish, which used the sea anemone as its home in a mutualism relationship.

Another example is that of the remora fish, which attaches itself to a shark using a disk on their head and detaches itself from the shark to eat extra food when the shark is feeding.

So we can see that the fish have learned how to use their environment to their advantage and to survive in it.

Using Tools

Some fish have also learned to use their surroundings as assets to improve their living conditions.

For example, tusk fish have been observed trying to open shellfish with the help of a rock to feed off of them.

Fish have also been known to show learned behavior, the kind that has been demonstrated by the five monkeys experiment.

An example is the Atlantic Cod, which, during a lab test, was made to pull a string to get food out of an automatic feeding machine.

Before long, the Atlantic Cod was seen readily pulling the string for food.

This learned behavior shows great potential for the evolution of fish, even if it isn’t motivated by human-like intelligence.

Finding a Mate

Another similarity between humans and fish is the effort both the animals put into finding a mate.

Like most other animals, fish also look for their ideal partner before releasing their thousands of clusters of eggs into the sea.

Some fish change their appearance, show patterns, or even perform acts of devotion to win over their desired partners.

Fish also decided which ones amongst them are more or less attractive.

For example, an experiment with guppies showed that when they were put in an environment with female guppies of all shapes and sizes, they preferred to mate with the largest one.

However, another group showed male guppies being exposed to average-sized female guppies (i.e., guppies that are of average attractiveness) did not have a specific mate preference.

These behaviors in finding a partner are very similar to those of other animals and therefore show that fish do indeed have a brain.

Feeling Pain

Fish do not have a neocortex in their brains, which is why scientists still debate over whether they can feel pain or not.

However, an experiment with bee venom injected in Remora fish showed it to squirm around and stop eating.

Even though this experiment showed that fish feel pain, we are not sure what the degree or the type it is compared to those of humans.

The Senses

Fish are not only intelligent and perceptive, but their brain is also developed enough to give them a complex system of senses so they can see, smell, and hear, taste, and touch as well.

These senses have helped fish survive in an environment as competitive as the ocean all these years.

They use their senses to judge their environment, to sense when predators are nearby and how to dodge them, to find prey and feed on them, and to have a specific idea of their whereabouts.

There are many different ways that fish use their senses; the common factor is that all sensory systems send signals to the brain.

We have mentioned some of the fish’s sensory systems below:

  • The Lateral Line – The lateral line is a complex system of sensory bundles and fibers that can detect pressure variation and fluctuation in the displacement of water around them. This system is only found in fish and some amphibians that live underwater, and it is a crucial system for aquatic animals to judge their surroundings.
  • The Otoliths – The Otoliths are essentially the “ears” of a fish even though they are not exactly like human ears. The otolith is the bone inside the ear of a fish, and it vibrates when a stimulus reaches is which the fish perceives as sound. These otoliths are highly developed, and fish can use the sounds they hear to judge their surroundings, the size of their prey, and the number of other animals around them. In fact, fish rely more on their ears than even their eyes even though their vision is very similar to that of humans.
  • The Eyes – Fish can see all the colors that humans can see through their eyes. However, many fish out there can also see ultraviolet. Despite that, the vision of a fish is similar to that of human beings. Fish can move their eyes independently from each other to be able to gauge their surroundings better. Fish do not rely on their eyes as much as most other animals do. This is because the ocean can be very dark, with little to no light entering the surrounding areas of the fish.Because of this, fish have other senses that have been greatly developed, like the lateral line and the otoliths, that give the fish a better idea of what is around them
  • Electric Sensory System
    Electric fish have an almost entirely different system of senses. These fish receive electric stimuli from their surroundings and can also release a weak current into the ocean. This helps them be able to take their surroundings in and have an accurate idea of whatever is happening around them.
  • Chemoreceptors
    Chemoreceptors include the sense of tasting and smelling. Chemoreceptors are present all over the body of most fish and can help them smell and taste their surroundings to see if there are any undesirable characters nearby.

Do Fish Have Feelings?

This brings us to the million-dollar question: Do fish have feelings?

Well, there is more than one school of thought.

Why We Think Fish Do not Have Feelings:

Many believe that fish are not able to process complex emotions like human beings do because they cannot see these emotions surface.

In fact, we can see that animals do not have the capacity to verbally express their emotions like humans do, and most animals cannot smile, cry, or change their expressions either.

Other than that, fish have a relatively small, less developed cerebral cortex, and they pretty much lack the center that is responsible for giving feelings and displaying emotions.

Fish are considered to be simpler than most other animals in this regard.

Because they live in an aqueous environment, their means of communication and survival are completely alien to most people.

We do not see them blink, change expression, or show any movements that can suggest that they are feeling something.

However:

Likely, we do not think that fish have feelings because we are trying to assess them as human beings.

Fish are a completely different organism from human beings, and therefore, we need to judge them by their criteria.

Maybe then we will be able to see if fish truly have feelings or not.

Why we Think Fish do Have Feelings:

Fish are still considered to be primitive beings.

This is quite untrue because fish, as we see today, are products of millions of years of evolution.

Like other animals, fish have evolved to interact with their environment, sense stressful situations, express their stress, and communicate with other fish.

Of course, they do all of this in a way that is foreign to human beings, so we assume that they are primitive.

Here are some of the ways fish likely show emotions:

Sounds

We, as human beings, have no idea what sounds a fish makes.

Even if we go scuba diving, we will never really hear fish the way we can hear other animals.

But this does not mean that fish do not communicate.

They make lots of sounds and communicate in ways that are so foreign to us that we have not exactly interpreted much as of yet.

We don’t know for sure if fish can use the sounds they make to express their emotions verbally, but it is still quite likely.

Temperature

Other than that, experiments have been conducted showing that fish display something called “emotional fever.”

Emotional fever is a response to stress shown by cold-blooded animals where their body’s temperature increases by a few degrees when they are in a stressful situation.

The experiment conducted on fish had a lot of them trapped in a net held above a tank of water.

The water was different temperatures throughout its volume.

When the fish were released from the net into the water, we saw that the stressed fish all clumped together in the warmer parts of the tank.

Now, we are still not sure how conscious this response is, but we can no longer say with certainty that fish do not have any feelings.

Is it Ethically Alright to Kill Fish?

So, we are now aware that fish do display feelings and emotions.

This brings us to another huge concern: Is it alright to not count fish in the fight for animal rights?

Many people look at small fish as decorative items to make their house look pretty.

They look at bigger fish as food and nothing more.

You must have noticed when discussing animal rights we talk about wildlife from the land a lot more than we talk about aquatic life.

Aquatic life is harmed much more than life on land for food and recreation.

Most of us are aware of the horrors fish have to face when they are taken in commercially: in large numbers and left to suffocate in the open air.

But it can be argued that commercial fishing is a necessity, and many people in the world survive on a staple diet that includes fish.

However:

What about angling recreationally?

Many people still go fishing and even fight for big and rare fish. The unsettling part is that this sport is still not considered problematic enough.

Some people do practice ethical angling where they do not fish in an area with an abundance of anglers.

Even so, it is troubling that fish are generally not counted amongst animals that deserve the same ethical rights that cats, dogs, and even birds do.

Related Questions:

What fish does not have a brain?

The fish we know commonly all contain brains in their skulls. However, a fish that does not have a brain is the jellyfish.

Along with not having a brain, jellyfish also do not have bones, gills, eyes, or even a heart. It is quite a simple animal if you think about it!

Do fish know when they are dying?

Likely, fish do not know when they are dying because, unlike humans or other developed animals, fish do not have a sense of self or identity.

Because of this, it is highly likely that they are unaware of their imminent demise and die without realizing it as well.

Do fish feel pain from fishing hooks?

Fishing hooks pierce the jaws of the fish, and to take the fish out of the hook; you have to rip the hook out of their mouth.

It is quite cruel when you think about it, and you can also see the fish wriggling on the line before it dies.

Fish do essentially feel “pain,” but it is likely not the same intense sensation that more developed animals feel because they lack the necessary development of the brain that causes pain as we know it.

Even though they do not feel pain in the traditional sense, they do release chemicals that signal them that they are under stress, which keeps the debate of angling being unethical alive.

Do fish get lonely?

Fish do not get lonely the way we humans tend to. Most fish are not particularly social animals.

You can see this if you have ever kept a singular goldfish in your house. It seems to be doing really fine on its own, when alone.

However, some fish are used to staying in numbers or “schools.”

If you separate these fish from their schools, they tend to get stressed out, and it might affect their health.

Do fish recognize their owners?

It may come as a surprise, but fish can recognize their owners.

Despite the myth that fish have an extremely short memory, fish have shown to have excellent associative memory and learning capacity.

Studies have shown that fish can recognize a human’s face if they have seen it a certain number of times.

So yes, fish can recognize their owners!

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