14 Most Dangerous Fish You Should Avoid At All Costs

Many dangers lurk in the depths of the ocean. Some are hidden beneath the waves, while others swim alongside us. Of all the creatures in the sea, fish are among the most dangerous. 

They may not seem like much, but they can pack a powerful punch. Some fish are poisonous, while others can deliver a painful sting. And then there are the fish that have razor-sharp teeth.

So, which fish should you avoid?

Here are 14 of the most dangerous fish in the world.

1. The Great White Shark

Photo of a great white shark swimming in the ocean

The great white shark is one of the most feared predators in the world. It is found in cold, coastal waters worldwide and is known for its large size and powerful jaws. These massive creatures can grow to be 20 feet long and weigh up to 5,000 pounds.

Despite their size, great white sharks are incredibly fast and agile. They can swim up to 25 miles per hour and attack with devastating force. Great white sharks are responsible for most unprovoked shark attacks on humans. 

These attacks usually occur when the shark mistakes a human for its natural prey. While great white shark attacks are rare, they can be fatal. If you find yourself in the water with a great white, the best thing to do is to stay calm and swim away slowly.

Fun fact: They mostly reside in the coastal waters of Australia, California, and South Africa. Great white sharks have a great sense of smell and can detect even a drop of blood in the water from a quarter-mile away.

2. Tiger Shark

A photo of a Tiger Shark

Tiger shark is also considered one of the most dangerous sharks in the world. You can find it in  tropical and subtropical waters around the world. 

Just like the great white shark, it has a powerful jaw and razor sharp teeth. It eats a wide variety including other sharks! It is also known to attack humans. 

Fun fact: The tiger shark gets its name from the dark stripes on its body, which resemble a tiger’s pattern. The tiger shark is large, reaching lengths of up to 14 feet. It has a wide, blunt head and a powerful, muscular body.

3. Tigerfish

an angler holding a giant tigerfish

The tigerfish is a highly aggressive freshwater fish that is found in Africa. It preys on other fish, amphibians, and reptiles. 

It is considered one of the most dangerous fish in the world because of its large, razor sharp teeth. One of its species, the Hydrocynus goliath or the goliath tigerfish, can reach up to 5 feet long and weigh a whopping 45kg. 

Fun fact: While the tigerfish is freshwater, it can also be found in brackish water. This means that it can tolerate saltier water than most other freshwater fish.

4. Piranha

An angler handling a piranha

When most people think of piranhas, they think of a school of these ferocious fish tearing apart their prey. And while that is certainly a possibility, it is not the only thing that piranhas are capable of.

Piranhas are found in freshwater rivers and streams in South America. They are small fish, with most adults reaching lengths of only 8-15 inches. However, piranhas have a reputation for being aggressive and dangerous. 

These fish have razor-sharp teeth and powerful jaws that can easily tear flesh. Piranhas are also opportunistic predators, meaning they will eat just about anything they can catch including mammals!  mammals.

While piranhas typically do not attack humans, they have been known to do so if they feel threatened or if food is involved.

5. Barracuda

Photo of a barracuda

In the world of fish, few fish are as feared as the barracuda. 

This is a large, predatory fish that you can find in tropical and subtropical waters around the world. The barracuda is a long, slender fish with a large head and powerful jaws. It is also a fast swimmer and can even leap out of the water to catch its prey! 

Humans are not part of the barracuda’s diet, but they are known to attack swimmers and divers. In most cases, these attacks are not fatal but can be very painful. 

Fun fact: Adult barracudas can reach lengths of 6 feet (2 meters) or more. 

The most known type of barracuda is the great barracuda, also known as Sphyraena

It is the largest member of the genus Sphyraena, reaching up to 2.5 m in length and weighing up to 56 kg. With its large size and fearsome appearance, this barracuda is commonly found in tropical to subtropical waters along coastlines, bays, and harbors.

6. Red Lionfish

Photo of red lion fish.

These beautiful but deadly predators are among the most venomous fish in the world. They belong to the lionfish group, and the family Scorpaenidae, which contains many venomous fish.

They are native to the Indo-Pacific region, but they have been introduced to the Atlantic Ocean, where they are now a serious invasive species. Lionfish have long, flowing fins and 18 venomous spines that can deliver a painful, sometimes fatal, sting. 

They are voracious predators and have been known to eat more than 30 smaller fish daily. Their dorsal spines are connected to venom glands that can deliver a painful sting. The venom is not usually fatal to humans, but it can be very painful and cause nausea, vomiting, and breathing difficulties.

Fun fact: If they feel threatened, they will display their dorsal fins.

7. Candiru

photo of parasitic fish, candiru

The size of the Vandellia cirrhosa or candiru  may deceive you as it is only around one inch in length. However, its lack of size may fool you into thinking that it is harmless, but it is one of the most dangerous fish in the world.

Commonly found in the Amazon River, the candiru is a parasitic fish. And, it canenter the human body through, you guessed it, the urethra.

Once it enters, the fish travels up the urethra until it reaches the bladder. The candiru embeds itself in the bladder’s walls and feeds off the host’s blood. The fish will eventually grow and cause immense pain, bleeding, and sometimes death.

8. Stingray

Ai Stingray

Of the 750 known species of stingrays, only a handful have been implicated in attacks on humans. Most of these incidents occur when a ray is accidentally stepped on while wading in shallow water, and the victim receives the puncture wound from the stingray’s long, sharp tail spine.

In most cases, the wound is excruciating and, in rare cases, life-threatening. They have flat bodies with sharp spines on their tails that can reach up to 35cm in length.

When stepped on, they often lash out with their tail, leaving a deep and extremely painful wound. The spine fragments and venomous barbs embedded in the wound can cause serious infection.

9. Box Jellyfish

Ai Boxjellyfish

The box jellyfish is found in warm waters worldwide, including Australia, Hawaii, and the Gulf of Mexico. It has long, venomous tentacles that can reach up to 10 feet in length, and its sting is excruciating – often compared to being burned alive.

The box jellyfish’s venom is so potent that it can kill a human in just minutes. Its venom can cause the Irukandji syndrome, a condition characterized by an extreme rise in blood pressure, severe pain, and even heart failure.

There may be an overload of stress hormones,  causing hypotension and tachycardia. 

There are over 50 species of box jellyfish, but the one most commonly associated with human fatalities is the sea wasp.

This species is found in northern Australia.ts sting is so powerful that it can kill an adult human in just three minutes. Symptoms of a box jellyfish sting include intense pain, paralysis, and cardiac arrest.

10. Fugu

Photo of Fugu fish

Fugu, a  Japanese word for pufferfish, is also one of the most dangerous fish in the world. It may look harmless, but fugu contains tetrodotoxin, a potent and very deadly neurotoxin that is deadlier than cyanide. This poison is found in the fish’s liver, ovaries, and skin. 

If consumed, expect numbness, paralysis, and even death. In Japan, where fugu is considered a delicacy, half of reported food poisoning related deaths are due to fugu consumption

Fun fact: The fugu fish is a member of the Tetraodontidae family, which contains many other species of pufferfish. The fish is found in the northwestern Pacific Ocean, along the coast of Japan. It is also found in the East China Sea and the Yellow Sea.

11. Moray Eel

Photo of Moray eel

Although they look like snakes, moray eels are fish. They have long, snake-like bodies and sharp teeth that can do some serious damage. There are over 200 types of moray eels, most of which are found in tropical waters.

These eels hide in holes and crevices, waiting to ambush their prey. While they may not be the biggest fish in the sea, moray eels can be quite dangerous. Their sharp teeth are exceptionally strong, and they’re not afraid to use them.

The teeth are angled backward, making it difficult for prey to escape once caught. Moray eels will often attack divers and swimmers who come too close to their hiding spots. In some cases, they’ve even been known to chew through wetsuits.

They carry a toxin in their saliva that can cause serious pain and swelling. If you’re lucky, a moray eel bite will only result in a trip to the hospital. But in some cases, the toxins in their saliva can be fatal.

12. Electric Eel

An electric reel resting at the sea floor.

You might not think that an electric eel would be very dangerous to humans – after all, they’re only found in the Amazon and Orinoco basins. Wrong, these creatures pack a serious punch – up to 600 volts, to be exact.That’s enough to kill a human or give them one heck of a shock! 

So how do these creatures generate so much electricity? Electric Eels have a special organ in their bodies that contain cells called electrocytes.

When the eel wants to generate an electric charge, it sends a signal to these cells, causing them to release ions into the water. This creates an electric current that can stun or kill their prey.

And if that wasn’t enough, electric eels can also discharge electricity in short bursts to deter predators. So, if you’re ever swimming in the Amazon and see one of these guys, it’s probably best to leave it alone.
Fun fact: Electric eels resemble a snake and can grow to be over eight feet long. Their skin is dark grey or brown, and their underside is usually light yellow or white. They are scales less, but their skin is smooth and slimy.

13. Puffer Fish / Blowfish

Close-up photo of a puffer fish

The name “pufferfish” might make you think these fish are all fun and games, but they’re quite dangerous.

All pufferfish contain a toxic substance called tetrodotoxin in their internal organs.

Its name comes from its ability to “puff up” by swallowing water or air when it feels threatened, making it hard for predators to eat them.

While the tetrodotoxin doesn’t affect the pufferfish, it can be deadly to humans. Just 1 gram of tetrodotoxin is enough to kill an adult human, and there is no known antidote. Symptoms of tetrodotoxin poisoning include numbness, tingling, and paralysis of the lips, tongue, and face.

This can progress to weakness, difficulty breathing, and cardiac arrest. This deadly toxin is found in the pufferfish’s liver, intestines, and skin, so it’s important to avoid eating any part of the fish unless it’s been prepared by a trained professional.

14. Stonefish

Being one of the deadliest fish in the world, the stonefish is found in Australia, Japan, and the Indo-Pacific region waters. It is a bottom-dweller and often camouflages itself on the sea floor.

The stonefish is highly venomous, and its poison can kill a human within hours if not treated immediately. The sharp spikes on its back are full of venom; if you step on one, the poison will enter your bloodstream through the puncture wounds.

However, they do not use their venom to catch prey. They are very slow swimmers and wait for fish or other small animals to swim by so they can ambush them. But, if a human steps on them, they will not hesitate to use their venom.

There has been a development of anti-venom for stonefish stings, but it should be applied as soon as possible for the best chance of survival.

Be Careful in the Water

As you go about your day, it’s important to be aware of the dangers lurking in the water. These 14 fish are some of the most dangerous in the world and should be avoided at all costs. Whether it’s their venom, toxins, or electric shock, these fish can cause serious harm – or even death. So, next time you’re swimming, diving, or swimming, keep an eye out for these guys.