Candiru: Men Fear This Fish More Than Anything Else

If you were approached by a small fish while paddling, you’d hardly be scared, right? After all, how much damage could a little fish do? Well, that’s where you’d be dead wrong, especially if you’re a guy. Sometimes, a tiny fish, as you’ll soon discover, terrifies men more than anything else. And there are also many other horrifying creature of the depths. From paralysis-inducing horrors to fish that’ll literally impale you, coming up are some aquatic atrocities that are about to haunt your worst nightmares.

Candiru Fish

Lurking in the basins of lowland Amazonia, in countries such as Bolivia, Brazil, and Peru, is a deceptively fearsome creature called a candiru, or Vandellia cirrhosa fish. This species of parasitic freshwater catfish typically grows to just an inch or so. But as us guys know, it’s not size that matters, it’s how you use it! Which is certainly the case for the candiru.

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As a hematophagous, it feeds solely on the blood of other fish, hardly a mystery why it’s often dubbed the "vampire fish" then. Targeting larger fish, it parasitizes their gills and latches itself in place using the spines located at either side of its head. From there on, it’s an all-you-can-eat blood buffet for the candiru. But it seems it’s not just Amazonian fish that should fear this bloodsucker, men should too.

Sometime during the 19th and early 20th century, accounts of candiru fish attacking men in Amazonian waters began to grow. Word on the river was that when men urinated in the water, the urine would attract the candiru. So much so, that the fish would swim right up the man’s urethra.

Once there, the parasitic fish would hook itself in place with its spines and become near impossible to remove without surgery. Worse yet, once fully inside, the fish would allegedly lay eggs in the man’s bladder and eat away at his organs, ultimately proving fatal.

But as spinechilling as all this sounds, you’ll be pleased to know there’s a whole debate as to whether any of it is even true. Most reported cases happened in the 19th century and are purely anecdotal, from natives telling the stories to European explorers. With this in mind, there’s no hard evidence for any of it. However, in 2009, the wildlife documentary show, "River Monsters", interviewed Brazilian man, Silvio Barbosa, who was allegedly on the receiving end of a nasty candiru attack back in 1997.

According to Silvio, he’d been chilling around the Amazon River at Itacoatiara when he felt nature’s calling and took a tinkle into the water. The next thing he knew there was a sudden pain and, on looking down, Silvio realized with horror there was a tail hanging out of his you know what. Unable to remove it himself, Silvio ran to get medical attention.

The show even spoke to the urologist who dealt with Silvio, Dr. Anoar Samad. Apparently, by the time he saw Silvio the poor man was swollen, feverish, and in a very bad way. But, with the help of some tricky surgery, the candiru was eventually removed. River Monsters is held in quite high regard when it comes to credibility, meaning this account of a candiru attack is the only one that holds any real weight behind it.

Fish Swims Up Man's Urine Stream by River Monsters

But alas, Silvio’s gonna have to try harder than that if he wants people to believe his urological troubles. Most reputable sources, including Healthline, just aren’t buying it; there are too many inconsistencies in his story. Both the size of the fish and certain details about Silvio’s life differ in the urologist report compared to what Silvio has since said.

Not only that, but experts point out that for the fish to successfully ascend up a stream of urine, as Silvio insists it did, it’d have to be propelled with immense power, something the candiru just doesn’t have. That, plus the fish’s size relative to the, no offence fellas, tiny opening of a urethra, would make it pretty much impossible for it to burrow itself in there.

And the claims that the "penis fish" would be attracted to urine were discredited way back in 2001. With all this in mind, it seems more likely that Silvio and his urologist’s appearance on River Monsters was a chance to tell the tall tale for a quick buck. Even so, we might never know for sure.

Billfish

Billfish, if you aren’t familiar with the term, covers a whole bunch of saltwater predatory fish that are characterized by their long and pointed bills, like swordfish, sailfish, and marlins. And if you’re not wary of these guys, their razor-sharp appendages might have you looking like a human kebab!

Swordfish, for example, are large and powerful predators who use their bills to attack and mercilessly slice open their prey. If provoked, that same aggression can be directed at us humans, which isn’t usually an issue as they live in such deep waters. But it’s not unheard of.

Back in 2015, 47-year-old Hawaiian fisherman, Randy Llanes, jumped off Honokohau harbor in an attempt to spear a swordfish that’d been spotted in the waters. After spearing the fish though, disaster struck. Enraged, the provoked predator started thrashing around and delivered a fatal blow with its 3-foot bill. That’s awful, but it serves as a harsh lesson to all of us. Don’t mess with swordfish.

Unfortunately, it’s far from the only instance of billfish brutality. When 40-year-old Indian man Molli Joganna and his pals were deep-sea fishing in the Bay of Bengal back in 2022, they started having difficulty pulling one of their nets in. Knowing there must’ve been something huge in there, Molli jumped into the water to check it out, which was a big mistake.

As Molli swam over to the net, he was shocked to find a black marlin, colossal billfish capable of reaching over 15ft in length. Even worse, the terrifying creature escaped the net and came right for Molli. Black marlins can swim at an alarming 30mph, so Molli had no time to react before it pierced him with its sharp bill. Despite his pals’ best efforts to save him, he sadly didn’t make it.

This next fish, the needlefish, isn’t technically part of the billfish family. It belongs to the belonidae family, which also have sharp bills. However, while needlefish are much smaller, growing up to just 37-inches, the small are just as mighty! Though they’re not aggressive, if startled they’re prone to leaping out of the water, which can result someone nearby getting impaled.

While it might sound unlikely, it’s actually happened quite a few times. Back in 2020, 16-year-old Muhammad Idul was fishing when one pounced out of the water and landed right in his neck! Miraculously, Muhammad survived the blow and made it all the way to the hospital, where the fish was surgically removed. Others, however, haven’t been so fortunate.

In 1977, a 10-year-old Hawaiian boy tragically passed after one pierced him straight in his eyeball. And again in 2013, a Saudi man also lost his life after suffering one to the neck. So, unlike the candiru, there’s no doubt this is one fish you want to stay far, far away from.

Parasites

We often associate water with fish. But there’s a whole bunch of other creepy creatures lurking in there, including some very nasty parasites such as the Guinea worms. Native to Africa, these water parasites begin their life as minuscule larvae, and infect microscopic copepods, or water fleas, that reside in stagnant water. Consequently, people without access to safe drinking water might accidentally ingest these copepods, and in turn, Guinea worm larvae.

Once in the host’s digestive system, the copepods die. The Guinea worm larvae, on the other hand, thrive. Over the ensuing months, two of the larvae mate and the male dies. The female however blooms into a three-foot-long worm, with the girth of a cooked strand of spaghetti.

But if you’re infected with one of these grotesque creatures, you probably won’t even know about it until a year or so after you swallowed it. That’s because, around this time, your little friend will have slithered all through your body’s connective tissues and eventually arrived at your lower leg or foot. Then, a painful swollen blister will appear and you might feel feverish. Finally, the worm will wheedle its way out of your skin. Its aim? To find water and release the larvae it’s been cultivating inside your body.

With its head blistering through, the only option is to painstakingly pull the sucker out, which can take anywhere from several hours to several weeks! But you want the really bad news? Considering symptoms don’t show for a whole year, you might have one lurking in you right now. And the Guinea worm isn’t the only parasitic worm prowling the waters. There are blood-flukes, which are gnarly little creeps that cause a disease known as Schistosomiasis, which affects almost 240 million people worldwide, second only in numbers to malaria!

Larval forms of the parasite live inside freshwater snails in some countries in Africa, Southeast Asia and elsewhere. After developing a forked head, the blood flukes leave their snail hosts and live in the water itself. If a person enters infected waters, the parasites can penetrate their skin with that forked head. From there, they migrate through the host’s tissue, eventually blooming into adult worms!

The worms then mate inside you, producing eggs which travel to the bladder or intestine and are usually passed through urine or stool. Often, however, these eggs become lodged in the intestine or bladder, causing inflammation and scarring. Other schistosomiasis symptoms include abdominal pain, diarrhea, and in more progressive cases, even bladder cancer.

If you are unfortunate enough to get it though, it’s not all doom-and-gloom. The disease can be treated by a course of the drug praziquantel. But ideally, it’d be better to not have parasitic worms mating and wading through your insides in the first place. Putting our feet back on land for a moment, but still keeping things parasitic and wormy, let’s turn our attention to possibly the most disgusting creature yet: parasitic roundworms.

This parasite’s larval form is carried by mosquitos and deposited on humans when they bite. Once on the skin, the larvae burrow inside and migrate to the host’s lymphatic vessels where they grow into adult worms. This inflames the lymphatic system, which is not good at all.

Essentially, the lymphatic system is a network of organs, vessels, and tissues that move a thin watery substance, lymph, into different areas of the body. It’s a vital part of the immune system, because lymph removes harmful substances from your cells and delivers nutrients and proteins.

However, when infected by roundworms, it can’t function properly, a disease known as lymphatic filariasis, or elephantiasis. Because your body becomes unable to drain lymph, it builds up, particularly in the lower body, and results in mass swellings and gross enlargements.

If left untreated, this can eventually become so severe that sufferers’ kidneys and entire immune systems are seriously damaged. Luckily, certain drugs and chemotherapy can help during the earlier stages, however in many cases, surgery is necessary.

But as Sebastian from the Little Mermaid once said, ‘it’s better down where it’s wetter’, so let’s head back under the sea and check out our next nautical terror, which goes by the name naegleria fowleri. And not to be dramatic, it’s more commonly known as the brain-eating amoeba.

Naegleria fowleri is a single celled microorganism that primarily feeds on bacteria and is typically found creeping in warm ponds, lakes, and hot springs around the world. The one and only way the amoeba can make its way into the body is via the nose when a person is submerged in contaminated waters.

Once inside, the amoeba makes a beeline for the brain, which is where it gets down to business. Between two and five days post initial infection, a person will begin to experience headaches, fever, nausea, and vomiting. As the infection progresses, or rather, the amoeba eats away at the brain, symptoms develop into confusion, seizures, hallucinations, and even coma! And while the infection itself is rare, it takes just 5 to 22 days to prove fatal, and it’s fatal in a whopping 97% of cases.

Though the terror doesn’t stop there. Here's one more water-based parasite for you: the acanthamoeba. And chances are, you’ve already been exposed to it. Found worldwide in tap water and chlorinated swimming pools as well as soil, air-conditioning units, and even contact lenses, this single celled monster gets around.

Luckily for most of us, it’s only usually dangerous to people with an already weak immune system. But for those people, the consequences of exposure are brutal. Entering through the eyes, wounds, or nose, acanthamoeba causes a serious infection of the brain and spinal cord known as granulomatous amoebic encephalitis, or GAE for short.

The amoeba makes your brain swell, and leads to all kinds of nasty symptoms. Confusion, changes in personality, seizures, and even paralysis on one side of the body. Then, in 95% of cases, you kick the bucket. And while, if identified, there are some antifungal drugs that have proven effective in trials, most cases are, unfortunately, fatal. Because of course they are.

Driver Ants

Putting our feet back on dry land briefly but continuing the theme of horrors that can get inside you, let’s have a look at driver ants. These bad boys are capable of some serious damage.

Dwelling primarily in central and east Africa, these aggressive carnivores live in colonies of up to 22 million. Should they perceive you as an aggressor, the entire colony might start a swarm, and if they manage to catch up with you, you’re in serious trouble.

As well as potentially suffocating you with sheer numbers, their extremely strong locking jaws mean they pack a painful bite. In fact, their jaws are so strong that in East Africa, tribes use them like stitches, if they get wounded, they get an ant to bite both sides of the cut, then break off the body. The seal can last days.

The ants aren’t always so helpful though, with enough numbers, they can actually devour a human. There have been several reports of inebriated adults or infants suffering this exact fate. Though, if it’s any consolation, humans aren’t exactly their favorite dish.

In fact, according to Forbes, it’s possible that they only see humans as a threat and not food, meaning that while they might kill you, they won’t necessarily eat you. Nevertheless, it’s pretty terrifying to think that death by ant is technically possible.

Spiky Sea Creatures

With their smooth, slimy scales, it’s safe to assume that most fish are soft to the touch. However, some species are so prickly, they’re deadly. Take the aptly named crown of thorns starfish.

Native to coral reefs across the Indo-Pacific, this lil fella packs a powerful prick thanks to its upper surface being riddled with spiky venomous thorns. If you’re scuba diving and accidentally touch them, they’ll cut straight through your wetsuit, and the starfish’s saponins will enter the wound.

Saponins are toxins that cause immediate stinging pain, nausea, and tissue swelling that can last over a week! Not to mention the spines themselves can become embedded in your body, sometimes requiring surgical removal. The good news is, run-ins with this guy aren’t fatal and can usually be treated with cleaning, ointments, and antibiotics. Still, if you’re ever checking out a cool coral reef on vacation, stay away from the starfish.

Likewise, you might wanna steer clear of sea urchins. Over 1,000 different species dwell across the oceans, and they can all be identified by their huge spikes, almost resembling the spiky variant of the Karen cut. But much like if you touch a Karen’s spikes, some sea urchins, such as the Echinothuriidae, Toxopneustes, and Tripneustes, will sting you, jabbing you with their venom.

In most cases, this will cause swelling, pain, muscle aches, and tiredness, but in extreme cases can lead to breathing difficulties, infection, and even death. Thankfully though, that’s real worst-case-scenario type stuff. Most urchin stings can generally be treated with pain relievers, removing the spines, and a good wash. Better still, watch where you put your feet when you’re paddling in the sea and avoid them altogether.

However, not all marine prickles are so easily treated. Introducing the stonefish, one of the world’s deadliest fish. Named for its impressive camouflaging abilities, this tropical fish is relatively small, growing to just 20-inches long. But with its mohawk of venomous spines, the creature actually yields enough toxin to finish off an adult in just 1 hour!

Administering what’s known as verrucotoxin, the recipient will experience intense pain, respiratory weakness, and paralysis, potentially even ending with their demise. There is an antivenom, however it has to be given before the paralysis kicks in, or it’s lights out.

And you should also be aware of the in-laws, stonefish are closely related to the similar-looking scorpionfish. They’re not exactly the best-looking family. But while the scorpionfish isn’t as deadly, it also packs a mega painful prick! A fin-shake with one of these guys can leave you with breathing difficulties, nausea, diarrhea, seizures, and even paralysis.

Most people can be treated by simply removing any spines and cleaning the wound with soap and hot water, but it’s an ordeal you really don’t want to put yourself through. Unless you’re on Australian TV show Kings of Pain of course. The show follows a group of guys intentionally getting stung and bitten by various critters.

Sea Lamprey

This next sea creature is SO ugly that it virtually has no face at all. Looking like something that’s swam right from the depths of hell, this is the sea lamprey.

Native to the northern hemisphere, this parasitic demon spawn shares the nickname ‘vampire fish’ with the candiru, considering it also has a taste for blood. Which, if you remember, makes it hematophagous. As it slinks through the northern and western Atlantic Ocean, the sea lamprey preys upon other fish, latching onto them with its vortex of razor-sharp suctioning teeth.

After attaching, it uses its rough tongue to bore at their flesh then drains away their body fluids. You can set aside any dramatic visions of being hunted down by one of these parasitic bloodsuckers though. Experts assure that they’re relatively harmless to us and prefer cold-blooded fish to warm-blooded mammals. That said, lamprey attacks aren’t unheard of.

As well as the Atlantic Ocean, they also lurk in America’s Great Lakes. The famous Canadian long-distance swimmer Marilyn Bell successfully swam the 32-mile width of Lake Ontario in 1954 when she was just sixteen years old. She said lampreys constantly attaching themselves to her swimming suit and trying to feed on her was one of the biggest challenges of the swim.

That’s not like a few leeches clinging to you either, sea lampreys grow to a daunting 3 feet long. Such a monstrous one washed ashore in the Netherlands back in 2023.

Sea Snakes

It’s no secret that snakes are one of the most feared animals in the world. But if it wasn’t bad enough having to dodge them on land, some species have even colonized the ocean, and many of them you wouldn’t want to meet. There are over 60 different species of sea snake, though they don’t have gills. Instead, they must come up to the surface to inhale air.

The average sea snake has adapted to hold its breath for 30 minutes at a time, with certain species lasting as long as 8 hours! As well as most being able to absorb oxygen through their skin, all have one huge lung on their right side that’s almost the entire length of their body. This allows them to use it like a tank of oxygen for extended dives.

But what if you bumped into one on a swim? Well, one of the most venomous is the Belcher’s sea snake, just one drop of its venom and you’ll be a goner within minutes! In fact, a single drop is so potent it can wipe out an insane 1,800 people.

Fortunately, Belchers have a relatively timid and calm temperament, and usually need to be severely provoked in order to attack. Even if they do, they only inject their venom about one in every four bites. Still, if you’re a fisherman you should stay vigilant, as the majority of attacks occur when the snake gets tangled in a net.

In general, experts agree that sea snakes are fairly unaggressive, with one huge exception. The beaked sea snake. Described as ‘aggressive and readily provoked’ by the Marine Education Society of Australasia, this monster of the ocean should not be messed with. While attacks are still rare, it’s responsible for a whopping 9 in every 10 sea snake related deaths.

If you get on the wrong side of one of these beasts, it’ll dart towards you and sink its powerful fangs in to deliver a dose of debilitating venom. While not quite as potent as the Belcher’s, it’ll still cause serious damage to your diaphragm, and can lead to respiratory failure, paralysis, and death. Land or sea, it seems there really is no escaping the snakes.

Double Bar Rabbitfish

To look at it, the double-bar rabbitfish might seem completely harmless. However, in truth this Indo-Pacific brute is about to become the fish of your worst nightmares, quite literally.

While it’s difficult to see, they actually have venomous spines on their dorsal fins, which, when under stress, they’ll point at any fish or hand within fins-reach! And if you touch one, you’re gonna be in a whole world of pain. That said, the venom itself is pretty inconsequential and can usually be treated simply by placing the affected area under hot water. Problem is, if you’re having a nice swim and get suddenly plunged into excruciating pain, it could easily make you panic and drown.

The spines aren’t the only issue though. More dangerous is actually eating the fish, which will give you the bizarre effects of ciguatera poisoning. Bottom-dwelling shore reef fish, like the double-bar rabbitfish, feed on toxic algae known as dinoflagellates. These dinoflagellates contain ciguatoxin, which builds up in the fish over time and makes them incredibly dangerous to digest.

Interestingly, dinoflagellates can sometimes be seen as red patterns in the sea, a phenomenon known as a Red Tide. This happens when they go through a huge growth period, called a bloom. When fish like rabbitfish feed on this toxic algae, they themselves become contaminated, though they don’t get symptoms.

If we then eat the fish though, it’s a whole different story. You might suffer diarrhea, vomiting, itchiness, dizziness, hallucinations, and nightmares that can last months. Quite literally, as mentioned earlier, making this the fish of your worst nightmares!

I hope you were amazed at the candiru and other horrifying creatures! Thanks for reading.