Just because an organism is very small in size it does not rule out the idea that it might not have a brain.
And contrary to popular belief fishes have their own brains. Although anatomically very different, it serves the same function as any other organism.
1. The Fish Brain
The nervous system just like humans has the same work of picking signals from the sensory nerves.
The signal is then transferred to the brain via the spinal cord. The brain of a fish is divided into four parts – the telencephalon, the diencephalon, the mesencephalon, and the hindbrain.
The telencephalon basically consists of the cerebrum and the olfactory lobe and helps to process smells.
For any fish that has an enhanced sense of smell, it is very enlarged.
It consists of the pituitary Gland, thalamus, hypothalamus and pineal body. Its work is to relay messages between receptors and working cells.
It also maintains homeostasis, which is the process of maintaining a constant internal environment.
It is part of the brain that processes all the visual clues as it consists of the following – superficial white zone, central zone, deep white zone, and periventricular grey zone.
It is also known as the midbrain.
The hindbrain primarily maintains equilibrium and also helps in relaying messages between the spinal cord and the brain and it consists of the brain stem and the cerebellum.
1.2. How Do Fishes Use Their Brains?
Fishes have a central and peripheral nervous system which consists of the brain and the spinal cord, so most of their behaviour is directed by their brain, and fishes use their brains for a lot of activities and protecting themselves from predators is among the top.
So they use their brain for different defence activities like distracting predators, moving away from their nests and pretending to be injured.
This makes them smarter than their predators and shows that they are strategic thinkers.
Although difficult to believe but fishes have a long-term memory, and their memorization is pretty strong.
For example, goldfishes remember the colour of the food dispenser even after periods of abstinence.
Similarly, with other fishes also remember who has fought them before, who defeated them and they maintain their distance from them.
Other than food and organism memory they also have a very strong memory of place, so anywhere where they have been
2.2. Pain and Stress
Obviously, the reaction mechanisms of fish and humans are not the same, so they don’t show or express pain like screaming or something like that.
They have different behaviour patterns when they are exposed to some irritating chemicals they lose their appetites to indicate that they are in pain.
Fishes also have many neurotransmitters like endorphins that relieve pain. Pain receptors are known as nociceptors they are present in the fish’s mouth and head and help them to sense the pain.
Another pattern that has been observed is that fishes rub their bodies against the tanks or rock back and forth when they are affected by something unpleasant.
2.3. Social Skills
Like humans, fishes also live in social communities and even identify with each other. They become adaptive and comfortable in their settings and then have a problem shifting to new tanks.
They are very receptive to strong personalities around them and they modify their behaviour around predators and enemies to avoid any mishap.
Since females prefer males who are less aggressive, the male fishes in front of their female counterparts do not act very aggressively.
Some fishes are very smart compared to others. It is believed that Mantas are the smartest fishes in all, they have the largest brain size.
The electrogenic elephant nose fish is considered to be the fish with the highest IQ, as it has a very good brain-to-body ratio compared to most other organisms.
3. Fish Species and Brains
Goldfishes not only do they have brains, but they also have a very good memory.
Betta fishes are also known for a very good memory which is unlikely because they are so small and cute that people believed that they just have an aesthetic appeal.
Koi fishes have a long-term memory so much that they can even recognise their names and even some faces which they encounter repeatedly.
Starfishes do not have a brain they just have a very simple nervous system which helps them to make decisions.
4. Fishes Use Their Brains for Using Makeshift Tools
When we look at a fish we realise that the only body part that basically performs functions other than helping it to swim is its mouth.
So, basically to eat, to breathe or even to hold anything fishes use their mouth. They do not have any limbs. So they use tools to facilitate their life, their brains perform in a way that they use tools in place of the missing body parts.
For example, some fishes lay eggs on leaves. These loose leaves can be easily taken away from the nest when there is a predator.
They know how how to do their own drilling and find appropriate places to make homes. They even use secretions from their body for various purposes like protection, vegetation and distraction.
5. Final Thoughts
If a person is thinking of getting a pet fish, it seems to be a good choice.
These are low-maintenance and very beautiful creatures. Aquariums can be customised according to your space and are very peaceful to look at.
You can keep different types of fish and eventually, you will understand their behaviour with the tank as well as with each other. They are smart creatures who learn to live with each other after a while.