How Many Species of Fish Are There?

Fish are the most diverse aquatic animal that can survive in water. Scientists believe that some species are yet to be discovered. Every year, new species of fish appears. So, how many species of fish are there?

There are approximately 34000 different species of fish at present. The diversity is way more extensive than the total species of other vertebrates. By taxonomy, fishes are three types: jawless, cartilaginous, and bony fish. There are also different categories to specify the species, such as human usage, habitat, toxicity, brooding behavior, breeding behavior, locomotion, lifespan, etc.

The vast diversity can’t be defined in a single category. Thus, in this extensive collection, which one of these fish is your favorite?

How Many Species of Fish Are There?
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Diversity Of Fishes

These vertebrate animals can live in both salt and freshwater. However, the first species of fish was not fully vertebrate. It had a soft spine. But from the Paleozoic era, fish had developed several forms to adjust to their surroundings.

Around 70% of total fish species are found in the Pacific Ocean. And 20% of the species are in the second-largest ocean that is the Atlantic. The remaining species can be found in other oceans and several freshwater sources. 

However, new species are being discovered every year. So the total count is still on.

Species Of Fish

The massive diversity of 34000 thousand fish species can be categorized in different ways. Here are a few such categories:


The most obvious category of fish species is their habitat. According to the research, 58% of the total fish species live in saltwater, and 41% live in freshwater (lakes, rivers, canals).

Saltwater fish are also found in different types. 78% of saltwater fish live near the shoreline. They are called coastal fish who like to live on the relatively shallow continental shelf. Only 7% of saltwater fish live in the deep sea. They are also known as demersal fish.

Examples include blue shark, stone loach, Abyssobrotula galatheae, Death Valley pupfish, blind cavefish, sargassum frogfish, etc.


Taxonomy is the more scientific way to categorize different species of fish. By virtue of taxonomy, fishes are of three types.

Jawless fish: 

These earlier evolved fish have no scales, no jaw or bone skeletons. They have oral suckers to increase their movement speed. Lamprey and hagfish are the most common jawless fish.

Cartilaginous fish: 

They possess a cartilaginous skeleton and develop paired fins. But they don’t have any swim bladders. 980 species are in this category, and the popular ones are chimera, rays, and sharks.  

Bony fish: 

The bony fish are of two types: ray-finned fish and lobe-finned fish. These types of fish have a single bone, flesh, and paired fins. Lungfish, coelacanths, chondroitin, holostean, and teleost are some of the bony fish.

Human Usage

Humans don’t just use fish to eat. They also use different types of fish for decorative purposes, tourist attractions, and other commercial ways.

The recreational sports fish are used for entertainment purposes, especially in America. Some popular sports fish are swordfish, walleye, porgies, marlin, etc.


By toxicity, fish species can be categorized into three ways: non-toxic, poisonous, and venomous fish.

Though venomous and poisonous fish are basically the same, they deliver their toxins differently. The venomous fish deliver their venom through a bite, sting, stab, or envenomation. On the other hand, the poisonous ones don’t deliver any poisons. Their flesh itself is deadly.

According to a study, there are a total of 1200 species of fish that can produce and deliver venom.

Examples include pufferfish, spotted trunkfish, giant moray, reef stonefish, lionfish, stingray, stargazer, etc.

Life Span

The life span of fishes also has diversity and creates many species. Some fish species have existed for millions of years where some of them are found in this century and can live only a few days.

Well, the gobies species have the shortest life span among all. On the other hand, rockfish, orange roughly, koi, and Greenland sharks have a lifespan of more than 100 years.

The Atlantic tarpon, green sturgeon, and Australian lungfish have lived for more than 100 years. Some fish species can live more or less than 100 days.


The diversity of fish species is also dependent on their locomotion. For example, a seahorse has the slowest locomotion among all the fish. It can move one inch in a minute.

But if you look for the top speedy ones, you will see the names of bluefin tuna, sailfish, shortfin mako, and wahoo. 

However, some other species with weird locomotion, such as flying fish, have a record of 42 seconds of flight time. Tripod fish, handfish, mudskipper, climbing perches are also in this weird category.

Size & Shape

Size is another common category to diversify the fish species. From tiny ones (stout infant fish) to giant whales, you will see fish species of every size. Some heaviest fish species are whale sharks, ocean sunfish, king of herrings, catfish, whales, etc.

There are also some species with irregular shapes like boxes (humpback turret fish), floating seaweed (leafy sea dragon), etc.

Breeding Behavior

Not all the species live near-surface water. Some fish like the deep sea, and some stay in the middle. Therefore, it’s not easy for them to mate.

For example, a grouper can change sex based on the availability of the opposite gender. Toadfish have to sing on 100-decibel powers to find their mate. Anglerfish releases hormones in seawater to spread the news of reproduction and when it needs a mate.

Feeding Behavior

All the fish species adapt three types of feeding methods: suction feeding, ram feeding, and biting. 

Another characteristic of fish is that they are opportunists. It means it will eat whatever it finds available nearby. For example, some big fishes eat small fish present in their ecosystem, and some fish like sharks can even eat a dead whale if it’s hungry.


We know that fish can easily see any object in both visible and UV lights. But the mesopelagic fish have to modify their vision because they don’t get enough sunlight in deep water.

For example, four-eyed fish, two stripe damselfish, barreleye, flashlight fish have a unique modified vision.

Quick Answer of Some Popular Curiosity

Still have some curiosity after knowing about such massive species? Well, here are some quick answers that may help with interest!

Most Beautiful

Some fish are pretty famous for their beauty, such as butterflyfish, seahorse, clownfish, lionfish, angelfish, mandarin fish, etc.

Most Eaten

Tuna, shrimp, and carp are at the top of the most eaten fish in the whole world.

Most Rare

The cyprinodont diabolos, also known as devils hole pupfish, are the rarest fish in any geographic region.  

The Tastiest

The halibut, swordfish, salmon, red snapper, grouper are the tastiest fish in the world.

The Scariest

Goblin sharks, frilled sharks, payara, blobfish, anglerfish, lamprey, and finger heads are the scariest fish to people.

Most Costly

Bluefin tuna is now the costliest fish globally because of its quality and taste.

More fish query you may like

What Is a Group of Jellyfish Called?

Is Tilapia A Real Fish?

Is an Octopus a fish (A Mysterious Creature)?

Bottom Line

Despite having a place among vertebrates, fish have thousands of diversities. These different species have proved possible because of their adaptive power in migrations.

Hopefully, you have now learned how many species of fish are there and what categories are responsible for such massive diversity. Know your fish variety and go on your next fishing trip with enough knowledge!

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