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do fish have brains?

Do Fish Have Brains?

Is it just us or do fish get hard done by? Human perception of them is that they aren’t capable of memory or feelings, they simply swim about and try to survive. Do they actually have brains?

Maybe that is what they look like they’re doing from an outsider’s perspective. But, once you get to know them, fish are actually more complex beings than you might think. 

The short answer is yes, tropical fish do have brains. Like all living creatures, fish require a central nervous system to function. The brain is the most critical component of the central nervous system, and it is responsible for many of the fish’s functions, such as perception, movement, and survival.

In this article, we are going to dispel the myth that fish run off one cylinder and that they do in fact have brains. Sure, you probably don’t have the next Einstein swimming around your fish tank, but they’re not as stupid as some people might think.

The fact that they are still here, however, is a testament to their will to live and their cunning sense of survival.  

What Is A Brain?

do fish have brains

Before we delve into the underwater world of fish, we thought it would be useful to first define a brain.

So, what is a brain? Brains are squidgy organs located inside the head of just about every living mammal, reptile, bird, fish, and insect on this planet. They are, in essence, the essence of life. 

Brains control our thoughts, memories, and emotions, as well as our ability to use our bodies.

Every motor skill and process that regulates the body of an animal is made possible by the brain; That includes touch, vision, breathing, temperature control, and hunger – yeah, it’s important. 

However, the brain doesn’t create magic on its lonesome. It is connected to the spinal cord which makes up the central nervous system.

This is the system from which all nerves extend and send signals back to the brain via the spinal cord. Life is mindblowing and it is the brain that makes the impossible, well, possible.

Do Fish Have Brains?

In short, yes, fish have brains. All of them do. Sure, jellyfish may not be so lucky to have a brain or a central nervous system, but they get along just fine bobbing about the oceans.

While a fish’s brain is significantly different from a human’s brain, it is still a complex and highly evolved structure. Fish brains are divided into different regions, each with its unique functions. For example, the forebrain is responsible for processing sensory information, while the midbrain controls movement and behaviour.

Fish species, though, are actually a whole lot more intelligent than people like to give them credit for. 

For instance, with no brain, how would your pet fish ever know when or how to swim up to the surface when it’s feeding time?

How would they know to swim over to the front of the fish tank when you walk over and get excited about the possibility of feeding? Who knows, maybe there’s even a little affection in there as well.

Studies have shown that tropical fish can learn and remember tasks and have a remarkable ability to navigate through their environments. This behaviour is evidence of the fish’s ability to use their brains to make decisions and solve problems.

None of these intellectual acts would be possible without a brain ticking away behind the scenes. Okay, so exactly how intellectual are fish you ask? You’re about to find out. 

Red Devil Cichlid Tropical Fish
There is certainly space for a big brain…

How Intellectual Are Fish?

Intellect is defined as the process of retrieving and storing memory that is then used under new contexts and to conceptualize skills.

In simple terms, intellect is an animal’s ability to understand the world, learn from experience, and teach itself new skills that help make life easier and better. 

Fish are smart little creatures with plenty of intellect behind their eyes. Intellect can be found inside your home tank when a new feature piece or fish arrives on the scene.

The fish who already call your tank home won’t just unassumingly swim over to these new arrivals. They won’t go near them until they can deem that the new object/ fish isn’t going to harm them.

This is their brain that is processing this new information and ensuring their safety by being wary of the unknown.  

A study carried out by Macquarie University concluded, that, in comparison to their body mass, fish actually have larger brains than insects and other creatures.

In fact, their brain size is even comparable to some primate species. Of course, their brains are no match for us humans, but we are an anomaly in the animal kingdom. 

Another interesting fact about tropical fish brains is that they continue to grow throughout their lives. This unique feature allows fish to adapt to changing environments and situations, such as when they outgrow their current habitat

How Big Is A Fish Brain?

How Big Is A Fish Brain?

Comparing the brain sizes of animals can only be successfully achieved when you compare them in terms of body weight and size. This is the only fair way to do it.

Why? Because even though small animals have tiny brains, compared to their overall body weight and size, they may have a large brain and be very switched on as a result. 

Where fish are concerned, even though they have larger brains compared to some insects and primates, they are still considered to have small brains when measured against most vertebrate species. 

However, not all fish were created equal, and sharks tend to buck this trend and then some. Everyone knows how intellectual sharks are. They haven’t managed to survive and thrive for over 450 million years through luck and guesswork.

They are highly refined apex predators with the brains to prove it. In fact, even though sharks are immense creatures, on body weight and size scale, their brains outmatch human brains quite considerably. 

Of course, your fish tank’s species won’t be quite as clued up as sharks. What this does prove, however, is that fish are smart. If sharks are so switched on then surely their more friendly fish tank cousins know what’s up too? 

What Are Some Indicators Of Pet Fish Intelligence?

Other indicators of pet fish intelligence include the use of tools, building homes, feeling pain, creating enemies, and forming relationships with other fish and you.

That’s right, some pet fish species even have facial recognition abilities that ensure they know when they are likely to get fed and by who.

This is a great little video about fish being a lot smarter than many people give them credit for.


Fish are great pets. Not only are they low maintenance (except for fish tank cleaning day). Once you get to know their habits and the inner workings of your tank, you will understand that it’s a very dynamic place.

Some species get along, some despise each other, and some are friends with everyone. 

It is, therefore, far from a stretch to say that not only do fish have brains, but they are intellectually advanced little creatures. Their intellect is put to good use and that is in the order for survival.

However, although most of their intellect is used for survival, as is evidenced by this article, they have also learned to enjoy themselves along the way. 

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