The Ultimate Guide to the 9 Most Dangerous Fish in the World

With more than 35,000 species of fish in the world today, it’s not surprising that there are some deadly ones among them. However, not all deadly fish are large and aggressive. Ironically, some of the deadliest fish are the smallest. Some fish contain enough poison to kill a human adult, and not all of them have antidotes! Continue reading to discover 9 of the deadliest fish swimming in our oceans.

9. Goliath Tigerfish

The Goliath tigerfish is known as the most dangerous freshwater fish in Africa. Found in the Congo River Basin, these fish are highly predatory, feeding on anything they can catch.  Goliath tigerfish are incredibly fearsome with their large, protruding teeth. They are considered a larger, more aggressive version of the South American piranha. Goliath tigerfish are among the few freshwater fish in Africa that are actively known to attack humans. Weighing around 130 pounds, these fierce predators often attack unsuspecting swimmers. Each of their teeth is around 1 inch long, and there is never any worry about them losing them. As polyphyodonts, they will grow a new tooth for any that are lost or broken.

8. Wels Catfish

Wels catfish are enormous freshwater catfish that can grow to be 16 feet long. These giants are found in lakes and rivers across Europe. They are easily recognized by their broad, flat heads and huge mouths. Wels catfish eat worms, insects, fish, rodents, frogs, and birds. Their mouths contain rows of small but incredibly sharp teeth, and, while extremely rare, there have been reports of these fish attacking unsuspecting swimmers and fishermen.

7. Moray Eel

Despite looking more like a snake, moray eels are actually fish and are incredibly dangerous.  There are around 200 species of moray eels worldwide, and although most live in the sea, some are found in freshwater.  Most moray eels can reach 5 feet in length and don’t have pectoral fins, which causes some people to mistake them for snakes.  Moray eels eat mainly squid, octopus, crustaceans, and other fish.  They often reside in rocky crevices, and divers are often attacked by them.  Moray eels are incredibly vicious when disturbed and attack with lightning-fast reflexes. Their teeth are exceptionally strong and sharp, and are angled backward to prevent prey from escaping. This makes their bites extremely painful, and wounds usually bleed heavily.  Moray eels carry a toxin in their slime and mouth that destroys red blood cells. This toxin is thought to be the reason why their bites are so serious.

6. Boxfish

Boxfish (Ostracion cubicum) are very similar to pufferfish (next on our list), though not quite as lethal. Boxfish are between 10 and 24 inches and weigh about 2 pounds. They inhabit coral reefs throughout the Pacific Ocean and Indian Ocean, as well as the Southeastern Atlantic Ocean. They are distinguished by their box-shaped bodies and, in some species, bright yellow coloration with black spots. Boxfish eat algae, worms, and small fish. To ward off predators, boxfish release a toxin called ostracitoxin through their skin into the surrounding water. They are typically not a threat to humans, though ostracitoxin can cause a severe reaction when it comes in contact with human skin. Some boxfish are deadly if eaten uncooked, and most people avoid eating them entirely because of their similarities to pufferfish.

5. Pufferfish

One of the most dangerous fish in the world is the pufferfish. There are more than 120 species of pufferfish, ranging in size from 1 inch to more than 2 feet long. Pufferfish are found in most tropical and subtropical waters, and they puff up into a ball when they are threatened or disturbed, hence their name. They have large spines on their skin, which become visible when they are puffed up.

However, looking fierce is not their only defense, as most pufferfish contain tetrodotoxin.  Tetrodotoxin is a poison that is 1,200 times more deadly than cyanide. This powerful poison is located in the liver, ovaries, and intestines of pufferfish. Even touching a pufferfish is dangerous. One pufferfish contains enough poison to kill 30 adult humans.  What’s even more chilling is that there is no known antidote!

Pufferfish are also a Japanese delicacy known as fugu. Chefs must undertake rigorous training and hold a special license before they are allowed to prepare the food. Even the slightest mistake could be deadly, with diners potentially paying for the meal with their lives.

4. Great White Shark

No list of deadly fish would be complete without the great white shark. Great white sharks are responsible for the highest number of unprovoked attacks on record. With around 300 teeth and an estimated bite force of 18,000 newtons, the great white is a fierce predator. These apex predators have an excellent sense of smell and can detect blood from a quarter of a mile away.  Great white sharks are located in the coastal waters of most major oceans and regularly eat fish, whales, dolphins, sea turtles, and seals.

Scientists believe that great whites do not intentionally attack people, but are simply doing a “taste test”. This is when they leisurely swim up to someone, often someone surfing, and take a bite to see if they are edible. This is very different from when they are intentionally hunting, as they rocket up to their prey from beneath and land a devastating bite. Unfortunately for us humans, even a taste test can be deadly.

3. Oceanic Whitetip Shark

Oceanic whitetips inhabit tropical seas around the world and are distinguished by their white-tipped fins. Although the great white shark, tiger shark, and bull shark have more recorded attacks on humans, the oceanic whitetip is generally believed to have killed more people.

Oceanic whitetips are infamous for feasting on the survivors of a US Navy ship during World War II. The USS Indianapolis was sunk on 30th July 1945 by a Japanese submarine.  Approximately 890 crewmen were stranded in the water for four days while they awaited rescue.  Only 316 survived. According to survivor reports, 150 people were killed by oceanic whitetips. Oceanic whitetip sharks are also credited with causing a large loss of life when the RMS Nova Scotia sank in 1942.

2. Lionfish

Lionfish are incredibly venomous fish native to the Pacific Ocean, though they are now found in the Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico. It is believed that their spread is the result of the aquarium trade. Lionfish are typically around 18 inches long and are characterized by their bright colors. Lionfish can have red, white, or black bands and have spiky fin rays that are venomous. They feed on small fish and invertebrates, swallowing their prey whole. Amazingly, they blow jets of water at their prey to confuse them before they capture them. Moray eels and sharks are some of the few known predators of these fish. Their stings can cause extreme pain, vomiting, and breathing difficulties. Although lionfish stings are not usually fatal to adults, they are extremely dangerous to children and the elderly.

1. Stonefish

The deadliest fish in the world is the stonefish, which has the ability to cause serious harm! Stonefish are between 14 to 20 inches long and wide due to their extremely wide pectoral fins. They are found in tropical waters, including the Indian Ocean, the Pacific, the Red Sea, and the Great Barrier Reef. Stonefish have crusty skin and razor-like spines and contain enough toxin to kill an adult in less than an hour, which makes them the world’s most venomous fish. They are ambush predators who feed from the bottom of the sea bed where they camouflage themselves on the floor.  Their crusty skin blends in with the rocks and sand, hence their name.

Stonefish deliver venom through the extremely sharp spikes on their back. This is so that they are protected from above when they sit on the seabed. Anti-venom is available, but it needs to be administered quickly, as paralysis and death can occur rapidly. Surprisingly, their venom is only a defense mechanism, and stonefish don’t use it to kill their prey.  Instead, they strike with their huge, powerful jaws and swallow their prey whole.  Stonefish eat reef fish and small invertebrates.