The Top 10 Deadliest Fish in the World

Ashvini Jayawardana

Fish are animals found worldwide in aquatic environments and are deeply intertwined with human life. The fish world is astonishingly diverse, encompassing creatures from a minuscule 7-8 millimeters to colossal giants reaching 60-65 feet, and displaying a remarkable array of body sizes, colors, and characteristics. According to the scientists, the initial emergence of fish occurred during the Cambrian Explosion, about 530 million years ago. Since then, they have spread out to all water-rich habitats worldwide evolving and diversifying into numerous species.

Fish are primarily classified by their habitat, being either saltwater (marine) fish or freshwater fish. As of 2022, the ‘Fishbase’ database, a comprehensive resource on fish species, listed approximately 34,800 identified fish species globally, with about 250 new species being added annually. Scientists estimate that about 51% (roughly 18,898 species) of these fish inhabit freshwater environments (lakes, rivers, and swamps). The remaining species are marine fish.

Fish have long served to survive life on earth, being a crucial food source for many organisms, including humans. Even their waste provides valuable nutrients like nitrogen and phosphorus that are essential for primary food production, highlighting their significant role at the very base of the food pyramid. Beyond their use of food, fish have been utilized for decoration, entertainment, and even as a form of therapy to promote mental and physical well-being since ancient times.

Despite its beauty, this underwater world is a constant battle for survival for both its inhabitants and those who venture into it. A natural cycle of predator and prey governs life there, leading to the evolution of various survival mechanisms. Some fish are inherently aggressive hunters, while others possess deadly venoms or poisons making them extremely dangerous to their predators as well as any other creature that makes them stressed.

This article will explore the top 10 deadliest fish in the world.

No. 10: Viperfish

Scientifically known as Chauliodus sloani, the Viperfish is a deep-sea fish usually inhabiting depths of 500-3000 meters. Reaching about 25-30cm in size, this relatively small creature is said to have a short lifespan. Viperfish thrive in the cold, dimly lit bottoms of Indian, Atlantic and pacific oceans. It has a long, slender body with a big head, terminal mouth, and a whip like tail. It is said that the fish received its name of Viperfish due to its prominent, fang-like teeth. The most special feature the Viperfish has is the photophore, the organ that produces light. This feature helps Viperfish to attract prey, startle the predators and to communicate with others of its kind.

Despite the extreme potency and lethality of its venom, incidents of human harm by them are said to be not reported yet as their habitats are in ocean depths beyond human reach yet. Scientists have identified nine species of Viper fish to date, but research is challenging because they inhabit extreme depths of the ocean.

No. 09: Candiru

Candiru is a freshwater fish, and their habitat is Amazon River region. Known by the scientific name of Vandellia cirrhosa they are also called vampire fish, toothpick fish and canero fish. They usually grow into a size of 2.5 – 3.5cm and their appearance is translucent. This tiny monster’s food is said to be fed on blood. They parasitize the gills other fish in Amazon River. The candiru, a type of catfish, has three identified species.

Also, Historical records indicate past attacks on humans by this creature. They enter into the human body through urethra or through other genital parts, and suck blood and cause the victim in extreme pain. It is said that this may cause the victim hemorrhaging and in worst cases even cause death. However, according to some latest publications, past accounts of Candiru fish entering the human body through the urethra and parasitizing it are likely a myth. Experts now suggest these stories may have originated from the fact that the Candiru is a bloodsucker, and misunderstandings about its feeding behavior on fish.

But, given this fish’s reliance on and attraction to blood, claims of its harmlessness to humans are dubious. Furthermore, reports of victims cannot be ignored.

No.08: Lionfish

Scientifically known as Petrois, Lionfish is one of the magnificent creatures in the sea. They inhabit Indo-pacific coral reefs and are said to be adaptable to various types of environments and temperatures. They grow up to 12-15 inches and are believed to have about 15 years of lifespan under natural conditions.

The entire body of Lionfish is beautifully decorated with bright strips of Maroon, white & black, and with fan-like fins. However, 13 of its fins that extended from their spine are venomous. Lionfish sting can cause humans extreme pain and sweating in the first stage. But there are chances to verse the situation up to respiratory issues or even to paralysis. Lionfish venom is reported to contain a mixture of a neuromuscular toxin, which is a protein, and a neurotransmitter called acetylcholine.

To date, 12 species of lionfish have been identified worldwide, with the red lionfish and common lionfish recognized as invasive species. Environmentalists warn that these fish will face food scarcity in the future because of coral reef destruction caused by environmental pollution.

No: 07: Electric Eel

Electric eels are freshwater fish inhabiting the calm, slow-moving waters of South America. These large creatures can grow to a size of 6-8 feet and have a lifespan of approximately 15-20 years. Despite their name, scientists classify electric eels not within the true eel family, but as the sole member of Electrophorinae, a subfamily of Knifefish family (Gymnotidae). To date, three species of electric eel have been identified.

These animals possess three specialized organs that generate and deliver electric charges in 3 levels from strong to weak. They can produce powerful electric shocks, reaching up to 860 volts. They utilize electricity for hunting, defense, navigation, and communication. These three organs, known as electrocytes, comprise approximately 80% of the eel’s body. Although human fatalities from electric eel shocks are considered rare, the risk of drowning increases if the victim is weakened or unable to swim. However, electric eel attacks are documented to potentially cause respiratory issues and heart failure in humans.

No. 06: Piranha

Piranhas are freshwater fish inhabiting South American waters, including the Amazon River. They belong to the family Serrasalmidae, believed to be closely related to omnivorous fish. While approximately 60 piranha species have been identified, many primarily consume plant material or are scavengers. However, piranhas are generally known as extremely aggressive predators.

These fish can grow up to two feet in length and live for around 20 years, often living in groups. They possess a fearsome appearance characterized by a large mouth and sharp teeth.

Although piranha attacks on humans are considered rare and they do not typically target humans as prey, they are attracted to the scent of blood. Nevertheless, reports of piranha attacks on humans continue to surface from South American countries.

No.05: Great White Shark

The Great White Shark, the largest predatory fish in the world, can grow to 21 feet or more and weigh over two metric tons. Its lifespan is approximately 70 years. Great White Sharks are found in temperate and tropical coastal waters across all oceans. The scientific name for the Great White Shark is Carcharodon carcharias.

These predators primarily hunt large marine mammals such as dolphins, seals, and sea lions. They are also known to prey on smaller shark species and whales. While Great White Sharks are known as man-eaters, the average reported number of annual attacks is approximately 65-67, representing roughly half of all annual shark attacks.

Experts believe that Great White Sharks face significant threats to their survival due to human activities, including hunting, as well as global environmental changes.

No. 04: Tigerfish

The Tigerfish, a freshwater species native to Africa, is renowned for its aggressive predatory behavior. Scientifically classified as Hydrocynus vittatus, it belongs to the Alestidae family. Its most typical feature is its exceptionally sharp, dagger-like teeth, which remain visible even when the mouth is closed, contributing to its frightening appearance. While there are approximately 40 species of Tigerfish, the largest can reach lengths of 4.9 to 5 feet. These fish typically have a lifespan of 10 to 11 years and are highly sought after as game fish. Although most Tigerfish species are not considered a threat to humans, the Goliath Tigerfish is reportedly aggressive and known to prey on humans, making it the only African freshwater fish with such a reputation.

Reportedly, the existence of Tigerfish is threatened by agricultural activities, deforestation, pollution and overfishing, and therefore they are included into protected species list in Africa.

No. 03: Stonefish

The stonefish, a member of the Synanceiidae family, inhabits the shallow waters of the Red Sea and Indo-Pacific, often residing near coral reefs. Its common name is derived from its remarkable camouflage, which allows it to blend seamlessly with rocky or sandy seafloors, or coral reefs. Typically measuring 30-40cm in length and with a lifespan of 5-10 years, the stonefish possesses 13 dorsal spines that serve as venom delivery organs. This venom is employed for self-defense, not for hunting purposes. A sting from these spines can induce unconsciousness, breathing difficulties, seizures, paralysis, and even cardiac arrest in humans. Experts have identified the key components of stonefish venom as stonustoxin, hyaluronidase, and cardioleputin.

Currently Stonefish are reportedly facing habitat destruction and pollution due to human activities.

No. 02: Pufferfish

Pufferfish are known to inhabit both freshwater and marine environments. They can be found in the Atlantic, Pacific, and Indian oceans, as well as in rivers in South America, Southeast Asia, and Africa. Their scientific name is Tetraodontidae. There are reportedly about 190 existing species of pufferfish. They range in size from 3 to 24 inches and have a lifespan of about 10 years. The name “Pufferfish” comes from their ability to inflate their bodies by gulping water as a defense mechanism, making the fish almost double in size. They are also called blowfish, fugu, balloon fish, and toadfish, among other names.

Most species of this small predator are highly toxic, ranking second among the most poisonous vertebrates in the world. The toxin in pufferfish is called tetrodotoxin, which experts say is about 1,200 times more poisonous than cyanide. Pufferfish use this extreme poison against predators, especially when inflated, as they can release the toxin at any time. Touching a pufferfish can be dangerous to humans. You should not reach for or touch this creature, especially when they are puffed up, as their toxin might cause a fatal condition if ingested or if it directly contacts open wounds.

Tetrodotoxin is produced and accumulated in the skin and other organs of pufferfish. Reportedly, one pufferfish carries enough of this toxin to kill 30 adult humans. Despite this, they are a delicacy and are popular among seafood lovers. Tetrodotoxin poisoning can cause paralysis of muscles, including those in the respiratory tract, which can be fatal. Unfortunately, there is currently no antidote for tetrodotoxin.

Some species of Pufferfish have been listed as endangered by IUCN due to overfishing and degradation of their habitats.

No.01: Box Jellyfish

The box jellyfish, scientifically known as Cubozoa, is considered one of the most venomous creatures in the world, and arguably the most venomous marine animal. These jellyfish inhabit coastal regions of Northern Australia and the Indo-Pacific region. Characterized by a pale blue, transparent, cube-shaped bell, they can reach up to 10 feet in size and have a relatively short lifespan of approximately one year. To date, around 51 species of box jellyfish have been identified. Reportedly, many species of Box Jellyfish are considered endangered at present manily due to pollution, overfishing and climate change.

Box jellyfish venom is stored within nematocysts; tiny capsules located in their tentacles. They primarily use this venom to capture prey and defend themselves. The venom contains neurotoxins that target the nervous system, as well as cytotoxins or pore-forming toxins that cause local tissue damage. Box jellyfish stings can induce cardiac arrest in humans within minutes, often before the victim can reach safety. Less severe cases can result in intense pain lasting for weeks and leave prominent scars where the tentacles made contact.

Recently, a team of Australian researchers announced the discovery of a potential antidote for Australian box jellyfish venom. However, they emphasize that further research is necessary to determine the antidote’s effectiveness against severe stings and its ability to prevent heart attacks.

Conclusion:

While this article draws upon globally recognized information, diverse expert opinions may exist. As an example, scientific classifications sometimes exclude box jellyfish from the “fish” category. Regardless, all creatures hold a vital and unique role within the natural world. Despite potential harm to humans, their existence is undeniably crucial, a testament to nature’s design. However, this article will highlight the extinction threat faced by many of these species, stemming from both direct and indirect human actions alongside natural environmental shifts. Consequently, immediate and comprehensive contributions from all of us are essential to safeguard these remarkable animals on Earth.