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The World’s 10 Most Dangerous Fish

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Many people around the world rely on fish or fish-derived products for food and economic survival. The oceans and bodies of fresh water on Earth are home to over 30,000 different species. Many fish species’ beauty is highlighted in fish stores, aquariums, and home collections. However, some species have darker, more terrifying aspects. Some of these may attack humans, while others may deliver a poisonous dose if handled carelessly or not properly prepared for consumption. Some species are maligned because of their shocking appearance or because of their ferocious reputation in folklore and myth; however, one species, despite its cute and tiny appearance, threatens bathers in a very, shall we say, personal way.


The puffer, also known as swellfish or blowfish, is any of about 90 species of fish in the family Tetraodontidae that, when disturbed, inflate themselves so much with air and water that they become globular in shape. Puffers are found in warm and temperate regions all over the world, primarily in the sea but also in brackish or fresh water in some cases. They have prickly skin and fused teeth that form a beak-like structure with a split in the center of each jaw. The largest puffers can reach 90 cm (3 feet) in length, but the majority are much smaller.

Many species are poisonous; tetraodontoxin, a highly toxic substance, is especially concentrated in the internal organs. Although this substance is lethal, puffers are sometimes eaten. In Japan, the fish are known as fugu and must be cleaned and prepared by a specially trained chef.

Lionfish (Red Lionfish)

Lionfishes (Pterois) are any of several species of showy Indo-Pacific fishes in the Scorpaenidae (order Scorpaeniformes) scorpion fish family. They are known for their venomous fin spines, which can cause painful, but rarely fatal, puncture wounds. The fish have elongated dorsal fin spines and enlarged pectoral fins, and each species has a distinct pattern of bold, zebralike stripes. When disturbed, the fish spread and display their fins before presenting and attacking with their dorsal spines. The red lionfish (Pterois volitans) is a well-known species that is sometimes kept by fish enthusiasts. It has red, brown, and white stripes and grows to be about 30 cm (12 inches) long. The red lionfish is native to the reef ecosystems of the South Pacific. The species became established in reef ecosystems along the Eastern Seaboard of the United States, the Gulf of Mexico, and the Caribbean Sea in the early twenty-first century. Because of its rapid reproduction rate and the lack of natural enemies in those areas, it decimated local reef fishes and was designated as an invasive species.

Wildlife managers believe that lionfish were deliberately released into the ocean by pet owners along Florida’s Atlantic coast beginning in the 1980s, but damage to pet stores caused by Hurricane Andrew in 1992 may have allowed others to escape.


The candiru (Vandellia cirrhosa) is a parasitic catfish of the Trichomycteridae family found in the Amazon River region. It is translucent and eellike, and it grows to about 2.5 cm (1 inch) in length. The candiru lives in the gill cavities of other fish and feeds on blood. It has been known to enter the urethras of bathers and swimming animals and to attack humans on occasion. Once inside, it erects the short spines on its gill covers, causing inflammation, hemorrhage, and even death to the victim.

The Great White Shark

The white shark (Carcharodon carcharias), also known as the great white shark or white pointer, may be the fish that needs no introduction because it is one of the world’s most powerful and potentially dangerous predatory sharks. The white shark, who has appeared as the villain in films such as Jaws (1975), is widely reviled and feared; however, surprisingly little is known about its life and behavior. The modern species has been around since roughly 18-12 million years ago, during the middle of the Miocene Epoch, but its ancestors may date back to at least the Eocene Epoch (about 56-34 million years ago), according to the fossil record.

White sharks are responsible for numerous unprovoked, and sometimes fatal, attacks on swimmers, divers, surfers, kayakers, and even small boats in the areas where they are most common. A white shark will usually bite its human victim once and then flee. However, in many cases, the shark does not return for a second bite. If the victim is bitten moderately, he or she may have enough time to seek safety. However, in cases where a large bite occurs, serious tissue and organ damage may result in the victim’s death. A review of white shark attacks off the western coast of the United States revealed that approximately 7% of attacks were fatal, but data from other locations, such as South Africa, show fatality rates of more than 20%. Attacks in the waters off Australia have resulted in death rates of up to 60%.

Many researchers believe that shark attacks on humans are motivated by the shark’s curiosity. Other experts, however, believe that these attacks are the result of the shark mistaking humans for its natural prey, such as seals and sea lions. It’s also possible that white sharks plan to attack humans in areas where their usual prey is scarce.

The Moray Eel

Moray eels are thought to be more than 80 species, and they can be found in all tropical and subtropical seas, where they live in shallow water among reefs and rocks and hide in crevices. Moray eels are distinguished from other eels by their small, rounded gill openings and the absence of pectoral fins. Their skin is thick, smooth, and scaleless, and their mouths and jaws are equipped with strong, sharp teeth that allow them to seize and hold their prey (primarily other fish) but also inflict serious wounds on their enemies, including humans. They only attack humans when they are provoked, and when they do, they can be quite vicious.

Moray eels are typically brightly colored or marked. They rarely grow longer than 1.5 meters (5 feet), but one species, Thyrsoidea macrurus of the Pacific, can grow to be 3.5 meters (11.5 feet) long. Morays are consumed in some parts of the world, but their flesh can be toxic and cause illness or death. Muraena helena, a species of moray found in the Mediterranean, was a popular delicacy among the ancient Romans and was cultivated in seaside ponds.


Tigerfishes are named after their ferocity when caught, their fiercely predaceous habits, or their appearance. Tigerfishes of the genus Hydrocynus (sometimes Hydrocyon) are prized game fishes of the characin family, Characidae (order Cypriniformes) in African freshwaters. They are swift, voracious, salmon-shaped carnivores with daggerlike teeth that protrude when the mouth is closed and are marked with one or several dark, lengthwise stripes, depending on the species. There are five species, the largest of which (H. goliath) can grow to be more than 1.8 meters (6 feet) long and weigh more than 57 kg (125 pounds). The smaller the H. vittatus is regarded as one of the world’s best game fish.

Marine and freshwater tigerfishes of the family Theraponidae (order Perciformes) are small and usually have prominent stripes in the Indo-Pacific. Therapon jarbua (three-striped tigerfish) is a common vertically striped species that grows to be about 30 cm (12 inches) long. It has sharp spines on its gill covers that can injure an inexperienced handler.


Piranha, also known as caribe or piraya, are any of more than 60 species of South American razor-toothed carnivorous fish with an exaggerated reputation for ferocity. Piranha has been portrayed as a ravenous, indiscriminate killer in films such as Piranha (1978). The majority of species, on the other hand, are scavengers or feed on plant material.

The majority of piranha species never grow longer than 60 cm (2 feet). The colors range from silvery with orange undersides to nearly all black. These common fishes have deep bodies with saw-edged bellies, large, generally blunt heads, and strong jaws with sharp, triangular teeth that meet in a scissorlike bite.

Piranhas are found from northern Argentina to Colombia, but the Amazon River, which contains 20 different species, is the most diverse. The red-bellied piranha (Pygocentrus nattereri) is the most infamous, with the strongest jaws and sharpest teeth of all. This species, which can grow up to 50 cm (about 20 inches) in length, hunts in groups of up to 100 people, especially during periods of low water. If a large animal is attacked, several groups may congregate in a feeding frenzy, though this is uncommon. Red-bellied piranhas prefer prey that is only slightly larger or smaller than themselves. A group of red-bellied piranhas will usually spread out to look for prey. When an attacking scout is found, he alerts the others. Piranhas have excellent hearing, so this is most likely done acoustically. Everyone in the group rushes in to eat, then swims away to make room for the others.The lobetoothed piranha (P. denticulate), which lives primarily in the Orinoco River basin and its tributaries in the lower Amazon, and the San Francisco piranha (P. piraya), which lives in Brazil’s San Francisco River, are also dangerous to humans.

However, most piranha species never kill large animals, and piranha attacks on humans are uncommon. Although piranhas are drawn to the smell of blood, the majority of species scavenge rather than kill. Wimple piranhas (genus Catoprion) are a group of 12 species that survive solely on morsels nipped from the fins and scales of other fish, which then swim free to heal completely.


Stonefish are venomous marine fish found in the shallow waters of the tropical Indo-Pacific that belong to the genus Synanceja and the family Synancejidae. They are slow-moving bottom-dwelling fish that live in mud flats and estuaries among rocks or coral. Thickset fish with large heads and mouths, small eyes, and bumpy skin covered with wartlike lumps and, occasionally, fleshy flaps, they rest on the bottom, unmoving, blending almost exactly in form and color with their surroundings. They are extremely dangerous fish. They are difficult to see, but when stepped on, they can inject large amounts of venom through grooves in their dorsal-fin spines. These fish’s wounds are excruciatingly painful and, in some cases, fatal. A few other species of robust, warty fish are included in the family Synancejidae. They are venomous as well, though not as well-known as the stonefish.

The Atlantic Manta

Manta rays and devil rays are members of the family Mobulidae (class Selachii) of marine rays. Manta rays have fleshy enlarged pectoral fins that look like wings; extensions of those fins, which look like devil’s horns, project as the cephalic fins from the front of the head. Manta rays have short whiplike tails with one or more stinging spines in some species.

Manta rays, which are related to sharks and skates, can be found in warm waters off the coasts of continents and islands. They swim near the surface, propelled by flapping their pectoral fins and occasionally leaping or somersaulting out of the water. They eat plankton and small fish, which they scoop up with their cephalic fins.

The smallest manta ray, Mobula diabolis of Australia, is only 60 cm (2 feet) across, but the largest, the Atlantic manta, or giant devil ray (Manta birostris), can grow to be more than 7 meters (23 feet) wide. The Atlantic manta is a well-known species that is brown or black in color and is extremely powerful but not aggressive. Contrary to popular belief, it does not envelop and devour pearl divers.

The Electric Eel

The electric eel (Electrophorus electricus) is a long South American fish that stuns its prey, usually other fish, with a powerful electric shock. The electric eel is a long, cylindrical, scaleless fish that can grow to 2.75 meters (9 feet) in length and weigh 22 kg (48.5 pounds). The tail region accounts for roughly four-fifths of the total length of the electric eel and is bounded on the underside by an undulating anal fin that is used to propel the fish. Despite its name, it is not a true eel, but rather a characin fish related to piranhas and neon tetras. The electric eel is one of the most important aquatic predators in the varzea whitewater flooded forest.

Electric eels made up more than 70% of the fish biomass in one fish survey of a typical varzea. The electric eel is a slow-moving creature that prefers slow-moving fresh water, emerging every few minutes to gulp air. The electric eel’s mouth is densely packed with blood vessels, allowing it to function as a lung.The electric eel’s proclivity for shocking its prey may have evolved in order to protect its sensitive mouth from injury caused by struggling, often spiny, fish. The stunned prey is stunned long enough to be sucked directly into the stomach through the mouth.

The electric eel does not always bother to stun its prey, instead gulping faster than the prey can react. The eel’s electrical discharges may be used to prevent prey from fleeing or to cause a twitching response in hidden prey, causing the prey to reveal its location.

The tail region houses the electric organs, which are derived from muscle tissue enervated by spinal nerves and discharge 300-650 volts—a powerful enough charge to startle humans. These organs may also be used to aid navigation and communication with other electric eels.