They’re some of the most diverse animals in existence, found all around the world, capable of adapting to both warm and cold water.
There are more than 34,000 species of fish and (clearly) won’t be listing them all. In this article, we’ll be taking a look at the (generally recognized) types of fish.
- Lampreys
- Hagfish
- Sharks
- Rays
- Ratfish
- Lungfish
- Latimeria Fish
- Bichirs
- Reedfish
- Sturgeons
- Paddlefish
- Gars
- Bowfins
- Eels
- Herrings
- Carps
- Piranhas
- Salmonids
Topics
1. Lampreys
Scientific name (order): Petromyzontiformes
Lampreys are an ancient order of fish that are known for their parasitic behavior. They’re mostly found in fresh and coastal waters where they’re found to stick to the flesh of other fish and suck their blood to feed.
They resemble eels and snakefish, but they developed a special mouth with plenty of teeth that allow them to attach themselves to the flesh of a large fish.
These types of fish in the Great Lakes are considered a pest because of their parasitical behavior, as they’re capable of killing healthy fish through this method of feeding.
2. Hagfish
Scientific name (family): Myxinidae
Also known as slime eels, hagfish have an eel-like 20-inch-long body with naked skin, generally pink in color.
These fish are known for producing slime when endangered – the slime lets them escape as the predator loses its grip, but the slime can also obscure the vision of a predator.
They mostly feed on marine worms, but they’ve been recorded killing injured or sick animals and feeding on them. Frighteningly, hagfish can enter the body of a dead animal and eat the insides of their prey.
3. Shark
Scientific name (superorder): Selachimorpha
Sharks are some of the most feared animals of the deep, which is often unjustified, as these animals don’t find humans as satisfying prey and they more often spend their time chasing other animals.
They’re known to have sets of replaceable teeth that keep growing throughout their entire lives. The most famous species of shark are the great white shark, tiger shark, blue shark, hammerhead shark, and the extinct Megalodon.
Impressively, some sharks have developed electroreception – this sense allows them to feel the electromagnetic fields that every living being produces.
Hammerhead sharks have the most well-developed electroreceptive organs, allowing them to ‘see’ other sea animals in the pitch dark.
4. Rays
Scientific name (superorder): Batoidea
Rays are actually related to sharks, with the biggest differences being the position of their eyes, their gill opening, and their tail. Stingrays are appropriately named after their tail, which often has a sharp spine at the end of it.
Rays mostly feed on small animals found at the bottom of the seabed, such as snails, clams, and some smaller fish. These types of fish in Australia can reach amazing sizes, up to 23 feet, and they’re usually found in warmer waters around the world.
5. Ratfish
Scientific name (order): Chimaeriformes
Also called chimeras, these fish usually live at great depths (up to 8500 feet), where they scour the ocean floor for food, which usually includes crabs, clams, shrimp, and worms.
Some fish within this order have a venomous spine used for defensive purposes (it’s not dangerous for people, but it is painful). They’re rarely seen near people, though, as they don’t swim at shallow depths often.
6. Lungfish
Scientific name (order): Dipnoi
The six remaining species of lungfish are spread around Africa, Australia, and South America, and they’re characterized by their respiratory system. Unlike other fish, lungfish have lungs similar to those of mammals.
These fish use their lungs to breathe air – they’ll come up to the surface when there’s drought and water starts losing oxygen. However, these types of fish that can breathe air still prefer using their gills for breathing.
7. Latimeria Fish
Scientific name (genus): Latimeria
The only two living species of this fish are the West Indian Ocean coelacanth and the Indonesian Coelacanth, which are found in the Indian Ocean, particularly near Indonesia and on the east coast of southern Africa.
Unfortunately, the former is critically endangered.
These animals are often found in underwater caves where they hide from predators during the day. At night, they look for prey in the crevices of lava caves.
8. Bichirs
Scientific name (order): Polypteriformes
These fish are found in freshwaters of the Nile and parts of tropical Africa. They’re usually dark – either grey or black – with green coloration on the scales. This helps them blend in, as they’re mostly nocturnal.
They also have characteristic dorsal fins – they’re very small with edged tips, and there can be up to 18 of them on a single fish.
Bichirs have a well-developed sense of smell, while their eyesight is poor. Just like Latimeria, they hide during the day and hunt once the sun goes down.
They usually suck up anything not too big for their mouths, including, but not limited to smaller fish, insects, and worms.
Bichirs are popular as aquarium fish, where they have the same tendencies for meaty prey.
9. Reedfish
Scientific name (genus): Erpetoichthys
Also known as snake fish, reedfish is the only member of its genus, indigenous to the waters of western and central Africa.
They too are equipped with a pair of lungs on top of their gills, so they can breathe in water that isn’t well saturated with oxygen.
This species is nocturnal, mostly feeding on very small fish, snails, insects, and worms. They’re elongated and thin, with short fins, which is why they’re recognized as the type of fish that looks like a snake.
Unfortunately, the species is threatened because of habitat loss. Even though they’re considered a delicacy, fishing levels are not a threat to them at the time.
10. Sturgeons
Scientific name (family): Acipenseridae
There are 28 recognized species of sturgeon spread around the entire northern hemisphere – from tropical to subarctic waters.
Wherever sturgeons find themselves, they’re threatened by habitat loss and overfishing, which is why they’re considered a highly-threatened family of fish.
Sturgeons can grow very old, with some of them growing to 60 years of age. It takes them a lot of time to sexually mature, as most only have their first offspring around 20 years of age. They mostly feed on shellfish and small fish.
11. Paddlefish
Scientific name (family): Polyodontidae
These fish are one of the few families that are found almost exclusively in North America. This makes them possibly the largest freshwater fish in North America – they can reach 5 feet in length and weigh more than 60 pounds.
The Chinese paddlefish was declared extinct in 2019, while those fish could grow to a staggering 23 feet and weigh more than 1000 pounds.
These types of fish in the USA have electroreceptors, very similar to those of rays and sharks, and they use them to detect zooplankton, which is their primary source of calories.
12. Gar
Scientific name (family): Lepisosteidae
There are seven living species of gar, usually found in freshwaters of North and Central America.
They’re easily recognizable by their elongated bodies and elongated jaws, filled with sharp teeth. Because of the latter physical characteristic, gars are often recognized as the types of fish similar to alligators.
In fact, there is a species called ‘alligator gar’, appropriately named after its resemblance to the large reptiles. Another similarity they share with crocodilians is the method of predation.
Although they seem sedentary and slow, they’re opportunistic predators that grab anything floating on the surface. This includes other fish, but also small mammals, waterfowl, and small reptiles.
13. Bowfins
Scientific name (genus): Amia
Amia calva is the only existing species of the bowfins, found only in the eastern USA and southeastern Canada. Bowfins are bimodal breathers, just like some other species on this list, as they can easily switch from breathing both water and air.
These animals can be easily recognized by the very long dorsal fin, which is as long as the entire fish. Like gar before them, bowfins are also slow, stalking predators that hunt at night.
They usually eat small fish and insects. Despite their hunting qualities, they can last very long without any food.
14. Eels
Scientific name (order): Anguilliformes
Eels are elongated fish found in both fresh and salty waters around the world. Depending on the species, their size ranges from 2 inches to 13 feet, with the European conger being the heaviest of all eels with 240 pounds.
They lack well-developed fins, but they make up for it by creating waves that push their bodies through their water. Their swimming technique is very similar to the way snakes move on the ground.
The conservation of eels isn’t at its best currently, as they’re often overfished. Eels are a very popular food around Asia, and without fishing controls, some species could soon become extinct.
15. Herrings
Scientific name (family): Clupeidae
This family of fish is very common in the northern waters of the Pacific and the Atlantic, and because of their accessibility, they’ve become a very popular food around the entire world.
In fact, herrings are extremely important for marine fishing in Europe.
Herrings can grow up to 18 inches and weigh 1.5 pounds, but smaller species don’t grow longer than 6 inches. They usually swim in schools, and as such, they’re a crucial link in the ecological chain.
These fish are prey to hundreds of species, including whales, seabirds, dolphins, sharks, seals, tuna, and many others. In return, herrings feed on sea worms, krill, and plankton.
16. Carps
Scientific name (family): Cyprinidae
Originally from Europe and Asia, carps are an invasive species now found in Africa, North America, and Australia, with possible, but unconfirmed populations in South America.
Carps are short and large fish, which makes them an important food source for many predators, but also for people. Interestingly, they have the ability to spend months without oxygen.
This usually happens in lakes that freeze over. To survive, carps use glycogen and form lactic acid, converting it into ethanol and carbon dioxide.
17. Piranha
Scientific name (family): Serrasalmidae
Endemic to bodies of freshwater in South America, piranhas are omnivorous fish known for their powerful bite and deadly attacks.
They usually flock together and attack prey together – they’re usually capable of devouring other fish, mammals, birds, reptiles, and humans.
Attacks on people are extremely rare, though, and piranhas don’t represent a real danger to people. In fact, they’re willing to eat vegetation if no meat is available, which can happen in drought season.
The tales of piranhas killing and cleaning meat off of bones of another animal in a matter of seconds are wildly exaggerated, as it would take many hungry piranhas to do that. In real life, locals are known to fish, and even swim among piranhas.
18. Salmonids
Scientific name (family): Salmonidae
This family consists of salmon, trout, chars, graylings, and a few other species. With salmon as the representative of this family, these animals can reach 6 feet and 7 inches in length.
They always spawn in freshwater and have to travel through seas or oceans only to return to fresh water to reproduce.
Salmonids mostly feed on small fish and aquatic insects. In this family, salmon are especially well-known because of their salmon swim.
To breed, they have to swim upstream (and famously get caught by bears). After breeding, most salmon die.
Summary
Fish are an unfathomably large class and it’d be almost impossible to list them all. The fish on this list are the most well-known and most widespread groups of fish, ranging from freshwater fish to marine fish found all around the world.
These incredible animals have found creative ways to adapt their bodies to the environment around them and survive for hundreds of millions of years. Some of the largest and most impressive species were never seen by human eyes because they starved to death due to their sheer size.
