65 Fun Facts About Fish That Every Kid Needs to Know

Ever wondered what the smallest fish species in the world is? Or how many tastebuds a catfish has? If you’re looking for some fun facts about fish, then this blog post is just for you!

This article features 65 fun facts that will keep your kids entertained and teach them something new at the same time. Check out our list of interesting tidbits about these creatures that inhabit both fresh and saltwater environments around the globe.

Table of Contents

65 Cool Facts About Fish

There are over 30,000 species of fish

The interior of the Oceanarium Crocus City, over 5000 species of fish and other animals from all over the world. Moscow, Russia

Isn’t that cool?! From piranhas to jellyfish, the number of fish species on earth is simply mind-boggling! No wonder it’s so much fun to learn about fish! 

The word “halibut” means “holy flatfish” (hali=holy + butte=flatfish) 

The name “halibut” was coined by Pliny the Elder in his book “Naturalis Historia”, which was published in 77 AD. This book is widely considered to be the world’s first encyclopedia. Yay for Pliny!

The amazing Spotted Climbing Perch is able to ‘gulp’ oxygen from the air and can crawl over land using its strong pectoral fins in search of water

It’s necessary for them to do this because they live in swamps and slow-moving streams. These fish have special organs known as “labyrinth organs” that allow them to breathe air. Betta fish are another type of common fish that have this organ.

 Most fish reproduce by laying eggs

bubble nest in micro shot

Plenty of fish prefer to lay eggs, some fish like seahorses and pipefish are known as “live bearers” because they carry their eggs in a pouch that they keep attached to their bodies.

What’s the world’s smallest fish?

The smallest fish is Paedocypris progenetica which are only 0.31 inches (0.79 cm) long! That’s smaller than a penny!

Most brands of lipstick contain fish scales

fish scales close up

The scales are used as a stabilizing agent, which means that they help to keep the ingredients of the lipstick mixed together.

Fish breathe through their gills

Yes! Fish need oxygen, and gills work by passing oxygen from the water into their bloodstream through the blood vessels found in special tissues. 

Lungfish can live out of water for several years

That’s right – not only are they able to go days without water, they can do so for up to years! This is made possible pecial organs called “lungs” that allow them to breathe air. However, their gills still work when the rest of their body is in water!

Did you know, American Lobsters have longer life spans than both cats and dogs, living over 20 years?

Close up picture of an american lobster

That’s a long time to be around! In fact, these crustaceans can even live for 100 years or more if they are well taken care of during their lifetime. There is one other type of lobster known as the European Lobster which only lives about ten years, so it seems like American lobsters have longer life spans by quite a bit! 

Most fish can see in color and use colors to camouflage themselves or defend themselves and their territory.

Fish are very smart animals, and they can even see in color like humans! Most fish use colors to camouflage themselves or defend their territory.

They have special cells that allow them to detect different wavelengths of light, allowing them to see the world around them more clearly than people might realize. 

What’s the most common fish in the ocean?

A school of fish

The most common fish in the world’s oceans are called “Herring,” which is a deepwater fish that only feed at the surface at night.

People eat tons of it! It can be used to make things like herring roe (fish eggs), which we call “caviar,” or pickled herring!

Some fish, such as the great white shark, can raise their body temperature

They can do this because their muscles contain a special protein called “thermal ion channels.” These allow the fish to move ions in and out of cells quickly, which helps them create heat. This is an amazing adaptation for animals who live in cold water!  

Most fish don’t have eyelids

Half Yellow Dojo loach on the bottom of aquarium.

They have a protective film over their eyes that helps keep them safe from the water or anything else. It’s kind of like an eye lotion! If you’ve ever gotten saltwater in your eyes, this probably doesn’t sound so bad to you…

A fish does not add new scales as it grows, but the scales it has increase in size

That’s right – the number of scales on a fish’s entire body stays constant throughout its life! The applies to any kind of fish that has scales – be it fresh fish or deepsea fish. 

Catfish have over 27,000 taste buds, whereas humans have only 9,000.

Even though humans and catfish can both taste things, we don’t have nearly as many taste buds as they do! So it’s probably a good thing that they like to eat some of the same foods we do.

Fish can form schools containing millions of fish

School of fish Harlequin rasbora

Schools of fish can be enormous! They might not all actually touch each other, but they swim in a way that makes it look like they do. Scientists call this “shoaling,” and it’s often done to protect the school from predators.

What are the oldest fish in the world?

The oldest fish in the world are called “Bowfin” and they can live to be over 100 years old! They also happen to look like dinosaurs. Not many people get a chance to see these living fossils, though, because there aren’t very many of them left anymore.

Fish that have thin fins with a split tail indicate that they move very quickly or may need them to cover great distances

Swordtails (Xiphophorus helleri)
Image Source: Petco

Most fish have muscles along the top of their tails, which are used for swimming. These are known as “adipose fins.” Fish that have split tails tend to be more active swimmers and may need them to move quickly or cover great distances. 

Fish are cold-blooded

They have a hard time regulating their body temperatures, so they often need to swim in warm currents. Fish also might not be able to live in very cold water because it slows down the chemical reactions that allow them to function properly!

The fish in the middle of a school control the school

The fish on the outside of a school swim in loops, letting them keep an eye out for predators. The middle-sized fish are usually responsible for keeping track of where they’re going and making sure that nobody gets left behind!

What is the loudest fish? The answer is, the croaker

This fish is able to make low-pitched sounds that can be heard above water, and they do it by vibrating muscles in their swim bladder! This organ helps them control how much air is in their bodies. It also makes croakers very sensitive to movement underwater because the acoustic sounds tend to bounce off of things easily. 

Starfish are not fish. Neither are jellyfish

A starfish on a jellyfish in Dubai beach

Starfish and jellyfish are both part of the phylum “Echinodermata,” which means that they have a hard endoskeleton, skin with holes in it to let water in and out, and arms/tentacles.  

How can you tell a fish’s age?

The age of a fish is usually determined by examining their ear bones. These are called “otoliths,” and they grow rings like the ones on trees do! Each time it grows one, it marks another year in its life. Many scientists believe that this method is more accurate than counting growth rings on scales.

A ship has a heavy keel in the lower part to keep it from capsizing. Fish, on the other hand, have the keel on top. 

Bluefin tuna Thunnus thynnus saltwater fish in mediterranean

If the paired fins stop functioning to keep the fish balanced, the fish turns over because its heaviest part tends to sink, which happens when it dies.

Scales help fish to swim

Fish have a lot of tiny, microscopic “teeth” on their scales that allow them to grip onto prey and keep from being pulled off. They also help fish to swim by reducing drag as they pass through the water! 

Since a fish’s jaw is not attached to its skull, many fishes can shoot their mouths forward like a spring to catch startled prey.

Pike fish isolated on white background. Head of trophy with open jaw with teeth

This is known as “suction feeding”, and it’s very helpful for a lot of fish! Some people think that the force from this movement might also help to draw prey towards their mouths.  

What percentage of a fish’s size is made up of the brain? 

Fish typically have quite small brains relative to body size compared with other vertebrates, typically one-fifteenth (0.06 per cent) the brain mass of a similarly sized bird or mammal.

On average, flying fish can glide 160 feet (50m), but have been known to glide as far as 660 feet (200 m). And they can reach heights up to 19 feet (6m).

The Australasian flying fish, Cheilopogon pinnatibarbatus melanocercus.

Flying fish have been clocked going as fast as 68 miles per hour (110 km/h) when they take off.That’s about as fast as a car!

How long do fish live?

The lifespan of a fish varies greatly depending on the type. Lots of fish can live up to five years or more while other types only get one year in which they’re mature enough to reproduce! The longest-lived fish on record is a rockfish that lived to be over 100 years old.

Electric eels and electric rays have enough electricity to kill a horse

Electric eels and electric rays can both produce around 600 volts of electricity! That’s enough to kill a small horse, but luckily it doesn’t usually last for more than a few minutes at a time. 

Fish are vertebrate animals

Fish Bone in a black backgroun

All fish have backbones, just like all other vertebrates! This means that they’re part of the “Phylum Chordata” which also includes birds and mammals.

Some fish, such as the herbivorous fish (grazers), often lack jaw teeth but have tooth-like grinding mills in their throats called pharyngeal teeth

These teeth are located in the throat of fish, and they can help to break down plants before they reach their stomachs!

Did you know that fish can get a sunburn? 

If a fish is out of its normal habitat, or if it just doesn’t have somewhere to get shade from the sun, then their skin can become damaged! This sometimes happens when they’re in an aquarium that isn’t large enough for them to avoid sunlight.

A fish can drown in water 

Featherfin squeaker
Image Source: commons.wikimedia.org

A fish’s gills need oxygen to stay healthy and active, so if they’re not in water, then they won’t get the oxygen that they need.

Do fish breathe air?

Some fish, like the lungfish and many species of catfish, can breathe air! This is called “air breathing” or “obligate aerial respiration.” Basically, it means that they have to take in oxygen from the air because their gills won’t work if there’s no water around. Sometimes you’ll see trout rising to the surface of the water in a lake or river – that’s not to breath air, but to eat insects. Anglers target these fish with fly fishing gear.

Although the fangtooth fish is only a few inches long, it has teeth about the size of a human’s.

fangtooth fish

They’re particularly large when they first grow in but shrink down as the fish ages.

Fish are speedy

The fastest individual fish is the sailfish, which can swim up to 68 miles per hour (110 km/h).

Most fish cannot swim backward 

silver shark - Bala Shark fish swimming fish tank underwater aquarium - Balantiocheilos melanopterus

Some kinds of fish can, such as sea horses and salmon.  

Which kind of fish can live in the coldest temperatures? The answer is the Antarctic ice fish, which have antifreeze in their blood?

They live permanently at -1°C. Crazy, right?

An inflatedporcupine fish can reach a diameter of up to 35 inches (90 cm). 

They can inflate their bodies when they feel threatened, which makes them look much larger.

Do fish sleep?

Sleeps Underneath A Whole Bunch Of Fish

Most fish do in some way, but it’s often for very short periods of time. 

The biggest fish in the world is the giant whale shark

They can grow to nearly 60 feet, or the length of two school buses. It weighs over 25 tons and eats mainly plankton. It has over 4,000 teeth, though they are only 3 mm long. 

Whale shark are too large to be kept as pets, but many types of sharks can be kept in freshwater tanks!

Fish talk to each other!

Iridescent Shark Catfish

They communicate with each other by making sounds and smells! Scientists can tell that fish are communicating in some way when they’re around one another because their behavior changes.

An estimated one-third of male fish in British waters are changing sex due to pollution in human sewage

This is due to chemicals that are found in some kinds of pharmaceutical drugs. These substances interfere with the hormones that usually control whether a fish will be male or female, making them change their sex!

Is it true that a fish surrounds itself with its snot to protect itself? 

Yes – parrotfish produce a mucus “tent” that completely covers them! 

Most fish have taste buds all over their body

This helps them find food by letting them taste different things. Fish like the goldfish don’t have very good vision, so they use their sense of smell and taste to help them get around.

How do fish swim?

Fish move with their tails and fins. They also use a technique called “ram ventilation,” where they open and close their mouths to pull in water and push it back out.

Saltwater fish need to drink more water than freshwater fish 

A family of Clown Fish Ocellaris. Uepi, Solomon Islands. Solomon Sea, Pacific Ocean

Saltwater fish lose a lot more water through their gills due to the salt.

Fish live in all sorts of waters

Fish can be found in nearly every body of water on Earth, Including rivers, lakes, ponds, and oceans!

The fastest fish is the sailfish

They can swim up to 68 miles per hour!


Did you know that fish have a specialized sense organ called their lateral line? 

They work much like a radar and helps them navigate in dark or murky water!

Most fish have a little salt in them

Epsom salts (Magnesium sulfate ) on the table

This is because they’re mostly made up of water and their bodies have the right balance for this! If there’s too much or too little salt in their system, then they will die.  

Do fish chew their food?

No, fish don’t use their mouths to chew.

They swallow their food whole! This is because most of them have very simple teeth that aren’t shaped like our own. Most kinds of fish just tear off pieces with their fins and eat these little bites.  

The slowest fish is a seahorse. It swims so slowly that a person can barely tell it is moving

seahorse in aquarium

The slowest is the Dwarf Seahorse, which takes about one hour to travel five feet. It even looks like it is simply standing up, not swimming.

Some fish are huge

The largest fish in the world is the whale shark, which can grow to be nearly 60 feet long. They eat mainly plankton and jellyfish!  

Hammerhead sharks can live in schools of more than 500 sharks

They hunt together for their food and will even protect each other from predators.

It was not until 1853 in London, UK, when aeration and filtration of water were understood, that people were able to keep fish as indoor pets

Before this, fish were kept in water wells and ponds. Water aeration and filtration made it possible to keep fish in fish tanks.

See also: Best filters for 10 gallon tanks 

The most poisonous fish in the world is the stonefish 

Reef stonefish (Synanceia verrucosa).

Its poison can kill a human if they’re stung just once. Its sting can also cause paralysis! 

 Are all fish edible?

Most fish are edible, but some kinds of fish may be poisonous to eat. Fish like the stonefish and pufferfish can kill a human if they’re not prepared correctly!         

The word “piranha” is from the Tupi (Brazil) pira nya and means “scissors.”

a pair of freshwater piranhas are looking for prey in a photo from behind a glass aquarium

The name comes from the fish’s sharp teeth, which are good for biting off chunks of meat.

Is there much salt in fish?

Yes! Much like humans, fish contain a little salt. 

Why do fish sometimes have a strong odor?

A fish can sometimes have a strong odor because of how it’s prepared. It may also be the way they eat, or their body type.  Fish that eat other animals will taste stronger than ones who just get nutrients from plants!       

Will the fish I catch and release die anyway?

The fisherman releases caught fish fry

No, fish who are caught and released usually live!

Seahorses are the only fish that swim upright

Hand touching a seahorse

Seahorse can swim upright because the water pushes them up. They also use their tails to move around like a propeller!  

The oldest fishhook ever found dates back to about 42,000 years ago

it was found in Sakitari Cave in Okinawa, Japan.

Conclusion

So there you have it! 65 fun facts about fish you need to know! Did you enjoy talking to your kids about fish? And if you’re a kid yourself, did you like this article? Do share it with your friends if you did, and drop us a comment to say hi!

Wanda is a second-generation aquarist from the sunny tropics of Malaysia. She has been helping her father with his freshwater tanks since she was a toddler, and has fallen in love with the hobby ever since. A perpetual nomad, Wanda does her best to integrate fish-keeping with her lifestyle, and has taken care of fish in three different continents. She loves how it provides a nice break from the hustle and bustle of life.

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