These are the most dangerous fish that exist

Lots of folks all over the globe rely on fish or fish-related stuff for their meals and money. There are over 30,000 types of fish swimming around in oceans and freshwater. Many of them are really pretty and you can see them in fish tanks or even have them at home. But some fish are kinda scary. A few of them might attack people, while others can make you sick if you don’t handle them right or cook them properly. Some fish get a bad rap because they look weird or because people tell scary stories about them. But there’s this one tiny, cute fish that poses a threat to swimmers in a pretty personal way.


The pufferfish, also known as swellfish or blowfish, is a type of fish that can puff up like a balloon when it feels threatened. There are about 90 different kinds of pufferfish in the Tetraodontidae family. They’re known for their ability to inflate themselves with air and water, making them round in shape. Pufferfish live in warm and moderate areas all over the world, mostly in the ocean but sometimes in slightly salty or freshwater too. They have tough, often spiky skin. Their teeth are fused together to form a beak-like structure with a split in the middle of each jaw. The biggest pufferfish can grow up to about 90 cm long, but most are much smaller.

Many pufferfish are poisonous; they contain a highly toxic substance called tetraodontoxin, which is especially concentrated in their internal organs. Even though this toxin can be deadly, some people still eat pufferfish. In Japan, where they’re called fugu, they have to be cleaned and prepared very carefully by chefs who are specially trained to handle them safely.

Red lionfish

Lionfish, also known as Pterois, are a group of eye-catching fish found in the Indo-Pacific region. They belong to the scorpion fish family and are known for their venomous fin spines, which can cause painful puncture wounds if they sting you, though it’s rare for them to be fatal. These fish have large pectoral fins, long dorsal fin spines, and each species has a unique pattern of bold stripes, like a zebra. When they feel threatened, they spread out their fins and may attack with their dorsal spines. One famous type is the red lionfish, which is often kept by fish enthusiasts. It’s striped with red, brown, and white and can grow up to about 30 cm long.

Originally from the South Pacific, red lionfish have spread to the Eastern Seaboard of the United States, the Gulf of Mexico, and the Caribbean Sea. Unfortunately, they’ve caused big problems there because they reproduce quickly and have no natural enemies. This has led to them wiping out local reef fish populations, so they’re considered invasive species. It’s believed that people might have released lionfish into the ocean deliberately, possibly starting in the 1980s along Florida’s Atlantic coast. Damage to pet stores caused by Hurricane Andrew in 1992 could have also let some escape into the wild.


The candiru, scientifically known as Vandellia cirrhosa, is a small, transparent catfish that lives in the Amazon River area. It doesn’t have scales, and it’s shaped like an eel, growing to about 2.5 cm long, which is roughly the size of your fingertip. This little fish survives by feeding on blood, often found in the gill cavities of other fish. Unfortunately, it’s not picky and sometimes it attacks humans too. There are scary stories of it sneaking into the urethras of people or animals who are swimming or bathing. Once it’s inside, it sticks out the spines on its gill covers, which can cause swelling, bleeding, and even death to the unlucky victim.

Great white shark

The white shark, also known as the great white shark or white pointer, is perhaps one of the most famous and feared predators in the sea. It’s been portrayed as the villain in movies like Jaws (1975), which has only added to its scary reputation. Despite its notoriety, we actually know surprisingly little about its life and behavior. Scientists think this shark has been around for millions of years, with its modern form appearing around 18 to 12 million years ago. However, its ancestors might date back even further, possibly to around 56 to 34 million years ago.

In places where they’re common, white sharks have been responsible for many attacks on people who are swimming, diving, surfing, kayaking, or even just in small boats. Usually, a white shark will bite once and then swim away. It’s rare for them to come back for another bite. If the bite isn’t too severe, the victim might have time to get help. But if the bite is big, it can cause serious injuries or even death. Studies have shown that around 7 percent of white shark attacks in the western United States are fatal, but in other places like South Africa, the fatality rates can be over 20 percent. In Australia, they’ve seen rates as high as 60 percent.

Some scientists think that these attacks happen because the shark is curious about what we are. Others believe that the shark might mistake us for its usual prey, like seals or sea lions. Sometimes, when food is scarce, the shark might even go after humans instead.

Moray eel

Moray eels are fascinating creatures found in warm seas all over the world. You can spot them hanging out in shallow waters near reefs and rocks, often hiding in cracks and holes. Unlike other eels, they have small round holes for gills and usually don’t have those side fins you see on other fish. Their skin is tough and smooth, without any scales, and they have big mouths filled with sharp teeth. These teeth help them catch their favorite meal, which is usually other fish, and they can also use them to defend themselves if they feel threatened, even against humans. Moray eels are typically brightly colored or marked and usually don’t grow much longer than 1.5 meters, although there’s one type in the Pacific that can reach up to 3.5 meters long!

Some people eat moray eels, but you have to be careful because their meat can sometimes be poisonous, making you sick or even causing death. There’s one kind called Muraena helena that the ancient Romans loved to eat. They even farmed them in ponds by the sea as a delicacy.


Tigerfishes are a group of fish with different species that earn their name because they can be quite feisty when they’re caught, they’re really good at hunting, or they just look like tigers. In Africa’s freshwater areas, tigerfishes from the Hydrocynus genus are popular among anglers. They belong to the characin family and are known for their sleek, salmon-like bodies with one or more dark stripes running along their length. These fish are fast swimmers and carnivores with sharp teeth that stick out even when their mouths are closed. There are about five species, with the biggest ones growing over 1.8 meters long and weighing more than 57 kg. The smaller ones, like the H. vittatus, are considered some of the best game fish in the world.

In the Indo-Pacific region, there are also tigerfishes, but they’re smaller and found in both saltwater and freshwater. They belong to the Theraponidae family and usually have bold stripes on their bodies. One common species is the three-striped tigerfish, which is about 30 cm long and has sharp spines on its gill covers that can hurt if you handle it carelessly.


Piranhas, also known as caribes or pirayas, are a group of fish known for their sharp teeth. They’re commonly found in the rivers and lakes of South America. They’ve got a bit of a scary reputation, especially in movies like Piranha (1978), where they’re shown as these super aggressive killers. But in reality, most piranhas are more into scavenging or eating plants.

Usually, piranhas don’t get much bigger than 60 cm long. They come in different colors, from silvery with orange bellies to almost all black. These fish have thick bodies, jagged bellies, and big heads with strong jaws filled with sharp, triangular teeth that can chomp down hard.

You can find piranhas from northern Argentina to Colombia, but they’re most diverse in the Amazon River, where you can find about 20 different species. The most famous one is the red-bellied piranha, which has the strongest jaws and sharpest teeth of them all. They usually hunt in groups, especially during low water when they might team up in groups of more than 100. But it’s rare for them to go into a feeding frenzy, especially over a big animal. They mostly like prey that’s just a bit bigger than they are or smaller.

There are a couple of species, like the lobetoothed piranha and the San Francisco piranha, that can be dangerous to humans. But most piranhas don’t attack people, and those attacks are pretty rare. Even though they’re attracted to the smell of blood, they usually scavenge more than they hunt. Some types, called wimple piranhas, just nip at other fish to get a snack and then let them swim away to heal.


Stonefish are a type of venomous fish that live in the warm waters of the tropical Indo-Pacific. They like to hang out near the bottom of the ocean, often among rocks or coral, and in places like mud flats and estuaries. These fish are pretty chunky, with big heads, small eyes, and rough, bumpy skin covered in wart-like bumps and sometimes flaps of flesh. They’re really good at blending in with their surroundings, so they’re hard to spot. But watch out! If you accidentally step on one, they can inject venom through their spiky dorsal fins, which can cause intense pain and sometimes even death. There are a few other types of fish in the same family as stonefish. However, they’re not as famous for being venomous.

Atlantic manta

Manta rays, also known as devil rays, are part of a group of marine creatures belonging to the Mobulidae family. They have wide bodies that are flatter than they are long. What makes them stand out are their big, wing-like fins that look like they could belong to a devil, with some extensions from these fins looking like horns. In some species, they have short tails with stinging spines.

These creatures, which are cousins to sharks and skates, prefer warm waters near continents and islands. They usually swim close to the water’s surface and move by flapping their big fins. Sometimes, they even jump or do flips out of the water. Manta rays mainly eat plankton and small fish that they catch by sweeping them into their mouths using their horn-like fins.

Manta rays come in various sizes. The smallest ones, like the Mobula diabolis found in Australia, can be as small as 60 cm across. But the biggest ones, like the Atlantic manta or giant devil ray, can grow to be over 7 meters wide! Despite their large size and sometimes intimidating appearance, these giant rays are harmless to humans. They’re usually brown or black and are known for their strength and gentle nature. Contrary to old stories, they don’t wrap themselves around pearl divers or eat them up.

Electric eel

The electric eel, scientifically known as Electrophorus electricus, is a long fish native to South America. It has a special ability to produce a strong electric shock, which it uses to stun its prey, usually other fish. This eel is long and cylindrical, with no scales and typically gray-brown, sometimes with a red belly. It can grow up to 2.75 meters long and weigh up to 22 kg. Most of its length is made up of its tail, which has a wavy fin underneath that helps it swim.

Despite its name, the electric eel isn’t a true eel. It’s actually related to other fish like piranhas and neon tetras. These eels are a big part of the underwater ecosystem in flooded forest areas called varzea. They make up a significant portion of the fish population.

Electric eels are pretty lazy creatures

They usually hang out in slow-moving freshwater. They come up to the surface every now and then to gulp air. This is because their mouths have lots of blood vessels that allow them to breathe air like a lung.

Their ability to shock prey likely evolved as a defense mechanism to protect their sensitive mouths from getting hurt by struggling fish. When they shock their prey, it stuns them long enough for the eel to swallow them whole. Sometimes, the eel doesn’t even bother to stun its prey, it just sucks them in quickly. The electric discharges can also be used to prevent prey from escaping. They can also make hidden prey twitch, giving away their position.

The electric organs in the eel’s tail are what produce the shock. These organs are made from muscle tissue and are controlled by spinal nerves. They can produce a charge of 300 – 650 volts, which is strong enough to shock humans. These organs also help the eel navigate and communicate with other electric eels.

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