These Are the Deadliest Freshwater Fish

The ocean is teeming with deadly fish, from sharks to stonefish, and you’re probably quite aware of these dangers whenever we go to the beach. However, you’re probably not as aware of the toothy fish that lurk in rivers and lakes around the world, unless you’ve ever watched the bizarre critters Jeremy Wade pulls out of the water in the series River Monsters.

Sometimes, we’d like to think of freshwater places like our favorite ponds and streams as being safe, free from the kind of bizarre and dangerous animals one expects to find in the ocean depths… But the deep sea isn’t the only place you can find terrifying aquatic creatures. Some of the world’s most terrifying creatures can be found right in your favorite freshwater spots.

Here we have compiled a featured list of the DEADLIEST freshwater fish in the world. If you dare, dive in!

African Tigerfish

African Tigerfish - Photo by Pla Waugh
Goliath African tigerfish. Photo by Pla Waugh.

If you saw an African tigerfish up close, you’d probably swim the other way. African tigerfish are rather scary-looking fish in the genus Hydrocynus, which are exclusive to the African continent. With long, sharp teeth, they gobble up any fish smaller than them, including members of their own species.

But, if that wasn’t enough, they are the only freshwater fish proven to prey on birds in flight.

The largest of all African tigerfish is the goliath tigerfish, which can grow up to 4.9 feet (1.5 meters) and weigh up to 34 pounds (15.5 kilograms). With giant teeth and a ferocious attitude, African tigerfish are dominant, terrifying predators; they’ve even been known to work together to take on larger land animals.

Hydrocynus_goliath_-_Poisson-chien_-_Aqua_porte_Dorée_05 - Photo by Loury Cédric
Goliath tigerfish teeth. Photo by Loury Cédric.

This creature is commonly regarded as the “demon fish” and boasts teeth longer than steak knives.

Goliath tigerfish are known to attack humans in The Congo, but this is probably a case of mistaken identity, and humans are not normally on the menu. In the murky waters, splashing sounds and shiny objects are attractive to the hungry tigerfish.

Tigerfish are mainly found in Africa, although they are present in South East Asia, as well as South America. Although generally they are not considered dangerous to humans, one species—the Goliath tigerfish—has been reported to prey upon unsuspecting humans. Scary stuff.

Dogtooth Tetras

Hydrolycus tatauaia. Photo by Clinton & Charles Robertson.

In the aquarium trade, tetras are known as the tiny, iridescent freshwater fish that school together in little tanks. But, in South America, you will find the biggest, scariest tetras in existence. These tetras, known as dogtooth tetras, have massive fangs that they use to impale smaller fish.

The most notable of these fish is the payara (aka “the vampire fish”), which can grow to lengths of 3.8 feet (1.17 meters).

Image: Wikimedia Commons

Now, should you be afraid of dogtooth tetras? Probably not. They’re not nearly big enough to cause significant damage, and they don’t tend to hunt in hungry schools like piranhas. Nevertheless, their toothy grins places them among the deadliest fish in the Amazon.

Muskellunge

muskellunge-esox_masquinongy-public-domain
Muskellunge. Public Domain.

Muskellunge or “muskie” are a familiar sight in lakes and rivers of northern North America. They greatly resemble their relatives, pikes and pickerels, and we’d even say they look like freshwater barracudas. Growing up to 7 feet (1.8 meters) and weighing nearly 70 pounds (32 kilograms), they are the largest members of the pike family.

In their range, muskellunge are apex predators, and there is very little that they won’t eat. They blend in perfectly with the underwater vegetation and use their camouflage to ambush fish, frogs, snakes, ducklings, crayfish, and small mammals. Luckily, as humans, we’re pretty safe.

Wels Catfish

wels-catfish-silurus_glanis-photo-by-dieter-florian
Wels catfish. Photo by Dieter Florian.

Wels catfish are massive freshwater fish that are native to central, southern, and eastern Europe. They can even be found in coastal areas around the Baltic, Black, and Caspian Seas. These catfish also happen to be the largest of all true freshwater fish, growing to lengths of 16 feet (5 meters) and weighing up to 660 pounds (300 kilograms).

This means very few animals are off the menu. They diet consists of annelid worms, gastropods, insects, crustaceans, fish, frogs, rodents, ducks, and even other wels catfish. They have even been documented ambushing pigeons on dry land, capturing them and devouring them in the murky depths.

Alligator Gar

alligator-gar-photo-by-howard-cheng
Alligator gar. Photo by Howard Cheng.

Alligator gar are weird-looking freshwater fish that prowl rivers and lakes in southern North America. With their toothy, elongated snouts, they look very much like their namesake, the alligator, and they can rival alligators in size. The largest recorded alligator gar was over 8 feet (2.4 meters) in length and weighed 327 pounds (148 kilograms).

On top of that, alligator gar rival alligators in appetite. As sluggish ambush predators, they prefer to hang out just beneath the water’s surface, where they attack fish, waterfowl, and small mammals.

In addition to resembling alligators, alligator gar are rather unique among fish. Like other bony fish, they have gills and a swim bladder; however, their swim bladder also allows them to breathe air in bodies of water that would suffocate other fish.

Giant Devil Catfish

goonch-catfish-bagrus_yarrelli_sykes-illustration-by-j-swaine
Goonch catfish. Illustration by J. Swaine.

Native to South Asia, the goonch catfish is also known as the giant devil catfish. Why? Because it can grow up to 6.6. feet (2 meters) in length, weigh over 200 pounds (90 kilograms), and has a reputation for attacking humans.

Between 1998 and 2007, a goonch catfish (or group of goonch catfish) is believed to have been responsible for a series of attacks on people around the Kali River between India and Nepal. The catfish are thought to have developed a taste for human flesh after consuming human corpses left adrift in the river on funeral pyres. So, with that in mind, you probably shouldn’t go for a swim in the Kali River!

Freshwater Stingrays

Giant Freshwater Stingray - Himantura_polylepis - Photo by Barry Rogge
Giant freshwater stingray. Photo by Barry Rogge.

While “freshwater stingrays ” might seem like a ridiculous joke, freshwater stingrays are actually very real. They are not all in the same family, but they all inhabit fresh and/or brackish water.

Potamotrygonidae is a family of exclusively freshwater stingrays native to rivers draining into the Caribbean in South America. In the Amazon, these stingrays are especially feared, since they are impossible to see when wading through the murky waterways. However, they are generally small, and their barbs are not nearly as dangerous as the bigger, ocean-going stingrays.

Yet, on the other side of the world, the giant freshwater stingray stalks river and estuaries in Southeast Asia. This massive creature can grow up to 6.2 feet (1.9 meters) in width and 16.4 feet (5 meters) in length. On top of that, it has a single, serrated spine, which can grow up to 15 inches (38 centimeters) in length, making it the largest spine of all stingray species.

Unlike the smaller river rays of South America, the giant freshwater stingray’s spine can pierce bone, so you really DO NOT want to step on one!

Electric Eels

Electric Eel - Photo by Steven G. Johnson
Electric eel. Photo by Steven G. Johnson.

Despite the name, electric eels are not actually eels. They are species of knifefish native to the Amazon and Orinoco Rivers. Yet, while they aren’t eels, they are electric and can produce up to 600 volts and 1 ampere of current (600 watts), which is enough to kill a human, although the short duration of the shock makes death unlikely.

Generally, electric eels use their powerful shock to stun prey. This allows them to easily slurp up whatever helpless creatures are in range. This also allows them to shock or stun humans at a distance, which makes them difficult to capture or handle.

Piranhas

Red-Bellied Piranha - Pygocentrus_nattereri - Photo by FF23-fr
Red-bellied piranha. Photo by FF23-fr.

Piranhas are among the most infamous and feared freshwater fish. Native to rivers in South America, they share habitat with other dangerous freshwater fish like the electric eel and the Potamotrygonidae freshwater stingrays. Traveling in schools, they can strip carcasses to bone in minutes.

For the most part, piranhas leave people alone. However, if food is scarce and water levels are low (resulting in higher piranha concentrations), trouble can brew, and piranhas are responsible for a number of fatal attacks.

Children are the most frequent victims, but adults are not immune to their assaults. In 2011, piranhas in the Brazilian state of Piauí attacked and injured over 100 people, and on December 25, 2013, piranhas attacked 70 bathers in Argentina’s Parana River.

If you’re willing to watch a ridiculous film about mutated piranhas, watch Piranha 3D. It’s so terrible that it’s entertaining.

Bull Sharks

Bull Shark - Photo by Teddy Fotiou
Bull shark. Photo by Teddy Fotiou.

Sharks are toothy fish that strike fear into the hearts of many, but due to their intolerance to freshwater, they are mostly confined to the ocean. Even so, a handful of shark species can and do tolerate freshwater. But, as you’d expect, these “river sharks” are all rare and elusive. Except the bull shark.

Bull sharks aren’t related to the “river sharks”, and they aren’t exclusively freshwater fish, but they are diadromous, which means they are capable of traveling between saltwater and freshwater. They are one of the only sharks known to do this, and coupled with their aggressive nature, they are extremely dangerous. In fact, bull sharks are not just the most dangerous freshwater fish; they are the most dangerous of all fish.

Along with great whites and the tiger sharks, bull sharks are one of the three sharks that are most likely to attack humans, and they are responsible for a number of severe injuries and fatalities. Their preference for the murky conditions in coastal waters, estuaries, rivers, and lakes puts them directly into contact with people, who participate in water activities in these areas.

Snakeheads

The 16 Deadliest Freshwater Fish (#1 Might Surprise You)
Image: Vance Crain, Florida Fish and Wildlife, Flickr

These aggressive fish are now recognized as an invasive species. They can grow to more than three feet in length and although they normally prey on invertebrates, frogs, and smaller fish, they have been known to attack anything when they are breeding. One of their most unique attributes is the ability to survive out of water for up to four days.

This fish is aptly named due to its similarities with the slithery reptiles. These freshwater fish are present in Africa and Asia, with around 35 described species.

Candiru

The 16 Deadliest Freshwater Fish (#1 Might Surprise You)
These terrifying freshwater species belong to a family of parasitic catfish. While they typically feed on the gills of bigger fish, there have been reported incidents of candiru getting lodged into the urethras of men and women. Although the possibility is met with some debate, the thought itself is enough to keep many people from swimming in its natural habitat.

Arapaima

The 16 Deadliest Freshwater Fish (#1 Might Surprise You)
Image: Jeff Kubina, Wikimedia Commons

These fish are truly monstrous, growing to giant lengths and sizes. The biggest individual was measured at 15 feet and 220 pounds. These torpedo-shaped fish can be found in the Amazon River Basin, although their population numbers are unknown and considered Data Deficient by the IUCN.

Electric catfish

The 16 Deadliest Freshwater Fish (#1 Might Surprise You)
Image: Stan Shebs, Wikimedia Commons

These terrifying creatures belong to the catfish family Malapteruridae. They weigh up to 45 pounds and are capable of delivering an electric shock of 300-400 volts, which is more than enough to kill a human. Electric catfish are carnivorous animals.

Wolf fish

The 16 Deadliest Freshwater Fish (#1 Might Surprise You)
Image: Raymond Bowen, Flickr

The wolf fish, also known as the anjumara, is an aggressive, predatory fish native to South America. They can grow to lengths longer than a meter and weigh up to nearly 90 pounds. Wolf fish boast razor sharp teeth and although typically prey on terrestrial invertebrates, they have been known to attack larger animals, and are the apex predators of their environment.