The most dangerous fish in the world

Fish are among the most beautiful and fascinating creatures in the world. There are thousands of different species of fish in all colors, shapes, and sizes. But there are also dangerous fish. We did not write this article to scare you, but to let you know which fish to avoid.

Many people around the world depend on fish or products made from fish for their food and economic livelihood. More than 30,000 different fish species populate the Earth’s oceans and rivers.

The beauty of many species of fish stands out in fish stores and aquariums. Some species, however, have darker, more terrifying, more dangerous aspects.

If you are interested in learning more about fish, you can visit our category dedicated to collecting all the information about fish.

The most dangerous fish on the planet

Some species are reviled due to the characteristics of the fish, their appearance or their reputation due to legends and myths; However, one of the species, although pretty and small, threatens bathers in a very, shall we say, intimate way.


The candiru (Vandellia cirrhosa) is one of the most fearsome dangerous fish, it feeds on blood and is commonly found in the gill cavities of other fish.

But sometimes it can also attack other animals, including humans, by entering through excretory or genital openings, especially the anus, urethra, or vagina.

Once in the host, it extends short spines on its gill cover and can cause inflammation, hemorrhage, and even death in the victim.

This parasite is a catfish (catfish), a transparent, scaleless fish of the Trichomycteridae family that inhabits the Amazon River. It usually grows to a size of 2.5 cm, but specimens of up to 22 cm have been found.

stone fish

The sad-looking stonefish (Synanceia) is the most poisonous fish on the planet. With 13 sharp spines placed on its back, this fish has almost perfect camouflage, and is also capable of surviving out of water for up to 24 hours.

The stonefish’s powerful neurotoxic venom is not only life-threatening but excruciatingly painful.

Classified in the genus Synanceia and the family Synanceiidae, it is found in shallow tropical waters of the Indian and Pacific oceans.

They are dangerous fish, they are slow and they live on the bottom, living between rocks or coral. They are chunky fish with large heads and mouths, small eyes, and lumpy skin. They rest on the bottom, motionless, blending in with their surroundings in shape and color.

Most stings occur on the foot when stonefish are stepped on. Although this can be unimaginably painful, it is not nearly as dangerous as getting stung on the body which will almost definitely require immediate medical attention.

Such a sting increases the risk that the venom will cause respiratory paralysis and possibly heart failure, that is, death. Fortunately there is an antivenin and in fact it is the second most administered in Australia.

The White shark

Due to its starring role as one of the most powerful and potentially dangerous aquatic villains in movies like Jaws (1975), the great white shark (Carcharodon carcharias) has been much publicly maligned and feared.

However, surprisingly little is understood about his life and behavior.

In areas where they are common, white sharks have been responsible for various attacks, sometimes fatal, against bathers, divers, swimmers, surfers… even boats.

But it is also true that attacks against human beings are very rare, almost anecdotal. In fact, more people are killed each year by dog ​​attacks than have been killed by great white sharks in the last 100 years.

A great white shark usually inflicts a single bite on its human prey and then retreats. It rarely returns with the aim of inflicting another bite.

If the victim suffers a moderate bite, you may have time to seek protection. In situations where a large bite occurs, serious tissue and organ damage can result in the death of the victim.

Great white shark attacks in the western United States showed that about 7% of attacks were fatal. But data from other locations, such as South Africa, show fatality rates of more than 20%. Case-fatality rates as high as 60 per cent of attacks have been recorded in Australian waters.

Lion fish

The lionfish (Pterois antennata), mistakenly known as the scorpionfish, is part of several western Pacific and tropical Indian fish species in the family Scorpaenidae.

These dangerous fish have huge pectoral fins as well as huge dorsal fins, and each species bears a particular pattern of striking stripes like a zebra.

When disturbed, the lionfish spreads and displays its fins and, if it feels in danger, it will come forward and attack with its dorsal spines.

One of the best known species is the red lionfish (Pterois volitans), an impressive fish highly valued by fish enthusiasts.

Its body has colorful red, brown, violet and white stripes, and it grows to about 30-40 cm. Native to the reef ecosystems of the South Pacific, in the early 21st century, the species became established in reef ecosystems along the East Coast of the United States, in the Gulf of Mexico, and in the Caribbean Sea.

Their rapid rate of reproduction, combined with the absence of natural enemies in those regions, resulted in the decimation of local reef fish and their designation as an invasive species.


In movies like Piranha (1978), these dangerous fish have been portrayed as ravenous killers. However, most piranha species are scavengers or feed on plant material.

Most piranha species never grow larger than 60 cm. Colors range from silver with an orange underside to almost completely black.

These common fish have a tall body, a serrated belly, and a large, usually blunt head. They have strong jaws with sharp, triangular teeth that meet in a scissor-like bite.

Piranhas can be found from northern Argentina to Colombia, but the most diverse are in the Amazon River, where 20 different species are found.

The most famous is the red-bellied piranha (Pygocentrus nattereri), with the strongest jaws and sharpest teeth of any piranha.

This species can grow up to 50 cm, especially in shallow waters, and hunts in groups that can have more than 100 individuals. Several groups may converge in a feeding frenzy if a large animal is attacked, although this is unusual.

The piranha P. denticulate, found primarily in the Orinoco River basin and lower Amazon tributaries, and the piranha P. piraya, a species native to the São Francisco River in Brazil, are also dangerous fish for humans.

Most piranha species, however, never kill large animals, and piranha attacks on people are rare.

Although piranhas are attracted to the scent of blood, most species capture more than they kill. Some 12 species of the genus Catoprion survive solely by «stinging» the fins and scales of other fish, which then swim free to fully heal.

electric eel

Long, cylindrical, scaleless and generally grayish, sometimes with a red underside, the electric eel (Electrophorus electricus) can reach 2.75 meters and weigh 22 kg.

The tail area makes up most of the electric eel ‘s total length, which is surrounded along the underside by an undulating anal fin that it uses for propulsion.

The electric eel is one of the main aquatic predators in the whitewater flooded forest known as the várzea forest. In a study on várzea fish, electric eels accounted for more than 70 percent of the fish.

The electric eel is one of the dangerous fish that prefers slow-moving freshwater, where it rises to the surface every few minutes to catch its breath. The mouth of the electric eel is rich in blood vessels that allow it to use its mouth as a lung.

The electric eel’s tendency to stun its prey may have evolved to protect its sensitive mouth from injury by fighting, often spiny, fish. Surprised prey is stunned long enough to be sucked through the mouth directly into the stomach.

Sometimes the electric eel doesn’t bother to stun prey, it just swallows faster than the prey can react. The eel’s electrical discharges can be used to prevent prey from escaping or induce a twitching response in hidden prey, whereupon the prey reveals its position.

The tail region contains the electrical organs, which are derived from muscle tissue innervated by spinal nerves, and discharge between 300-650 volts, a charge powerful enough to stun a human. These organs can also be used to help the creature navigate and communicate with other electric eels.

Tiger fish

The tiger fish (Hydrocynus vittatus) is a fast, voracious, salmon-like carnivore with dagger-like teeth that protrude when the mouth is closed. Depending on the species, it may have one or more dark, longitudinal stripes.

There are about five species of these dangerous fish, and the largest (H. goliath) can measure more than 1.8 meters and weigh more than 57 kg.

In the Indo-Pacific, freshwater and marine fishes of the family Theraponidae are quite small and usually marked with black stripes.

The three-striped tigerfish (Therapon baraonga) is a common species, with vertical stripes about 30 cm long. It has sharp spines on its gill covers, which can injure a careless handler.


Moray eels (Muraenidae) differ from other eels in having small round gill openings and in generally lacking pectoral fins.

Their skin is thick, smooth and scaleless, while their mouth is wide and their jaws are equipped with strong, sharp teeth that allow them to grab and hold their prey, mainly other fish.

Furthermore, these dangerous fish can inflict serious injuries on their enemies, including humans. They are capable of attacking humans only when disturbed, and can be quite ferocious.

Brunettes are usually flashy or colored. They usually do not exceed a length of about 1.5 meters, but the Pacific species Thyrsoidea macrurus are known to grow to around 3.5 meters long.

These dangerous fish are eaten in some areas of the world, but their meat is sometimes toxic and can cause illness or death.

One of the species of moray eels, Muraena Helena, found in the Mediterranean, was a great delicacy for the ancient Romans, even cultivated in coastal lagoons.


The puffer fish, also known as the sea ostrich or sea porcupine, is actually any member of about 90 species of fish in the family Tetraodontidae (Tetraodontidae).

Pufferfish are found in warm and temperate regions of the world, mainly in the sea, but also, in some cases, in brackish or fresh water.

They have tough and usually prickly skins. The largest grow to around 90 cm long, but most are considerably smaller.

Many species of these dangerous fish are poisonous. They have a highly toxic substance, Tetrodotoxin, which is especially concentrated in the internal organs.

Although this substance can cause death, puffer fish are sometimes used as food. In Japan, where the fish are called fugu, they must be carefully cleaned and prepared by a specialized chef.

So far this post about the most dangerous fish on the planet. If you want, you can continue reading with the article 21 curiosities about fish by clicking on the previous link to quench your thirst for aquatic knowledge.

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