The Truth About That Fish That Climbs Into Urethras

The Truth About That Fish That Climbs Into Urethras

[INTRO ♪] The candiru is a legendary monster. This parasitic Amazonian catfish is said to swim up into the urethras of unsuspecting bathers and devour their genitals from the inside out. It’s a terrifying tale—and one that we’ve
actually told here on SciShow a couple of times. But science has shown that this story is just that—a story—and one that is too awful to be true. As far as scholars can tell, the tales began in the early 1800s. European explorers and naturalists trekking through the Amazon basin heard about the candiru from indigenous communities. As they explained in their reports, they were told the parasitic fish is attracted to human urine, so you should never pee in the Amazon river. You shouldn’t even pee into the water from dry land—the fish can supposedly swim up a stream of urine to find its way into a person’s urethra. And once that happens … well, there were some removal methods suggested. Some herbs can supposedly be used to dissolve the offending parasite. But the most effective method of removal is, of course, prompt amputation. And all of that makes for a great monster myth—but it doesn’t jive with science. The candiru of legend is most likely the South American catfish Vandellia cirrhosa. It’s a parasitic catfish that inserts its head into the gills of larger fish to drink their blood, so it might not be that far out to think it could insert itself into people, too. But it’s about five centimeters long and
about a centimeter wide. That’s small enough to fit in the gill openings of the fish it targets, but not small enough to slip into a human urethra. A urethra could be pried open, in theory, but these fish don’t have any appendages to do that with. Also, if a candiru did somehow enter a human urethra, it would quickly suffocate—so it wouldn’t be chilling up there drinking blood. But the biggest problem with this whole story is that the candiru isn’t attracted to human urine. Scientists used to think these parasites sought out the nitrogen-containing wastes—basically, pee—that fish excrete from their gills. That’s because these catfish often hunt
in turbulent, muddy waters at night, so it would make sense that they’d rely more on chemical attractants rather than visual cues to find their meals. And if they were sniffing for nitrogen-containing compounds like ammonia and urea to find their prey, it follows they’d also zero in on human urine since it contains some of the same stuff. But in 2001, marine scientist Stephen Spotte tested this assumption in the lab. He and his team exposed candiru to a range of attractants—fish slime, ammonia, amino acids, and, yes, even human urine—and the candiru didn’t go for any of them. The catfish did respond to the sight of goldfish, though—which suggests that, despite the murky depths it hunts in, it actually relies on eyesight to find its meals. Which brings us back to all those stories
about pee-seeking fish. As a 2013 review paper notes, medically confirmed
attacks by the fish on humans are very hard to find. Most of the stories were perpetuated by a few 19th century European explorers who might have misinterpreted oral accounts—accidentally, or willingly, for the sake of a sensational tale. None of them seems to have witnessed actual cases. In fact, there’s only one candiru-penis
incident that’s been medically documented. In 1997, a man in the Brazilian city of Manaus was allegedly brought into the hospital with a candiru wedged painfully in his urethra. A urologist was able to remove the fish after hours of surgery, and he wrote the whole thing up and published the case. But, other scientists question the veracity
of this account. For one, the patient insisted that the fish
swam up his stream of urine. This is an impossible feat: the small fish would have had to swim faster than the stream of pee to climb it, which is challenging, since the average human urinates at a brisk 8 to 15 milliliters per second. The fish would have also had to fight the
pull of gravity while swimming upward, and to make matters more complicated, it would have had to stay completely submerged in the urine since the air around the urine is not dense enough for the fish’s fins to push against. And that’s not likely since a person’s urine stream is generally pretty thin compared to a centimeter-wide fish. Now, some fish can jump pretty high—salmon, for instance, can leap up to 2 meters—but it’s not clear these catfish are able to jump out of the water at all, let alone well. And even if one did leap at a person’s genitalia, as we said before, it has no way to widen the urethral opening to get inside. And there’s no reason the fish would even do that in the first place since it isn’t attracted to urine. There are also inconsistencies with the urologist’s findings. He apparently kept the surgically removed
parasite. And, according to Stephen Spotte—who visited the urologist and saw the infamous intruder first hand—the fish was far too large to fit in a urethra, and didn’t show any signs of having been inside a human being. For example, it still had its spines—which the doctor had claimed were removed during the surgery. With all these inconsistencies, it’s almost certain that this case is a hoax—and, again, it’s the only documented case. In the end, there are several scientific reasons why these fish wouldn’t do this awful behavior. So if you decide to go swimming in the Amazon, your urethra should be safe from parasitic catfish. You might want to watch out for the piranhas, though. Or the electric eels. Or the bull sharks, or caimans… I’m just saying, the Amazon is still a dangerous place! Thanks for watching this episode of SciShow! If you liked learning the science behind this below-the-belt myth, you might like the truth-seeking done on our podcast SciShow Tangents. Every week, four people who work on SciShow get together to talk about science related to a central topic. There are different segments, like one where someone presents one true fact and two fake ones and everyone else has to try and figure out which is true. With stories like the candiru out there, it can be kind of hard to tell what’s real and what’s made up! Also, they tend to go on lots of sciency tangents, hence the name “SciShow Tangents”. You can check it out wherever you get your podcasts! [OUTRO ♪]

99 thoughts on “The Truth About That Fish That Climbs Into Urethras

  1. Nah Im Brazilian and can ensure that the Amazon is not that dangerous. All these animals cited in the end of the video are busy taking care of their normal lives. The ecosystem is balanced still, so they hardly would take a chance woth such a strange animal like us. Ive already swam in the Amazon and Im perfectly fine.

  2. European explores?

    EUROPEAN… explorers?


    [insert Law & Order DUN DUN here]

    Case cracked. I'll be in my office if you need me.

  3. I remember watching the interview from the supposed man who had the candiru in his genitalia. I was very young at the time. All news channels reported on that hahah

  4. I have a question maybe you guys could turn into a video.

    Do fish feel pain when hooked?

    I’ve tried looking into it but I can really only find info from people with an agenda one way or the other. Maybe you guys could handle this question better.

  5. As a Brazilian, that's one less scary animal to frighten foreigners with. 🙁 At least we have a spider with a bite that gives you a raging erection! Be scared Australians, you got nothing on us! 😀

  6. There's a discovery channel bit on these. They show a surgery clip of a fish being removed from somebody. They said it ate the flesh of the urethra as it went up, rather than suck blood.

  7. First of all, with all the “death and destruction” in the Amazon river, why would you get into the river in the first place?

  8. More proof Google is listening. A few days ago I watched The Venture Bros. and the Monarch was gonna use these to kill Dr. Venture on tv. Not online. And now it shows up in suggested videos. I'm wise to your trickery Google.

  9. Once it's up there it spread to fins out so you can't pull it out.

    So what we've done here at true tails is we have sent a volunteer to that river.
    In which he will shove one of those fish up his urethra to prove it's true.

    We are here to prove animal Tails to be true to the best of our ability.

    And we here at animal tails hope you will join us for our first segment of animal tails.

    Watch in horror as we try to prove all the animal tails we can find to be true.

    Join us next week when we prove that the Wagon Wheel snake (sometimes called the Coachwhip snake) actually bites his tail and can roll down a hill chasing humans out of its territory.
    Then once he catches the human, he lets go of his tail and starts whipping him with his tail.
    Thus the reason they call it the Coachwhip snake

  10. Centimeter wide when it's full grown.
    But a baby's could do it looking for warmth.

    And as far as opening of urethra to get inside.

    Haven't you ever seen fish traps that use sticks.

    That actually was copied from how this catfish climbs into the urethra.

    It uses pelvic fins which are flexible and can wrap around a stick under each fin.
    It then spreads the urethra with the two sticks.

    And swims in between the two sticks thus jamming itself inside the urethra.

    And using its pectoral fins to push the sticks out to make it a nice tight seal. 😐

    And its pectoral fins get stuck open after helping to open the urethra to dislodge the sticks and the sharp spines of it poke into the urethra which starts the flow of blood.

    What you doesn't drink and it doesn't warm its body.
    It's just how it gets the sticks out. 😐

  11. Why cant i use google play music to listen to scishow tangents? The website just opens my goole play music app and thats all

  12. what if the supposed victim was performing an action whilst submerged in the water that would open up the urethra? Like, say, in a back and forth motion that would be more embarrassing than peeing in a river? maybe the guy got really horny, idk

  13. Isn't this the same fish Jeremy Wade did an episode about? With a guy who'd had one swim into his weiner while he was bathing in the river?

  14. I always thought it was an urban legend. Nobody wants to be bathing, swimming, washing their clothes and some yellow foam and three floaters go drifting by.

  15. you based all assumptions in this episode on an adult specimen…….. whats to say a juvenile wouldn't be small enough to swim in while swimming if you pee in the water? the speed of urine is slowed down in water just like everything else and holds the opening open. when you swim nude visually it can be mistaken as a fish by a smaller fish. under the right circumstances a small juvenile fish could swim in and get stuck. Just sayin…

  16. I fell for this myth, too. I saw a medical compilation show on TV once that included the "documented case" and fell for it. In my defense, in the show it was presented as a much smaller fish and the man was supposedly standing in the water while he was peeing.

  17. You should revise your human parasites video given you say the complete opposite in this video haha on the candiru

  18. Funny, I’d heard that it was mostly a hoax, but there were cases of fish swimming into women’s genitals and getting stuck while they were swimming or bathing. Regardless, I’m guessing the indigenous people just didn’t want people pissing in their river.

  19. There's one small problem here Scishow Jeremy Wade the host of River Monsters investigated a case in the Amazon of a man who had been allegedly attacked in this manner by a Candiru he spoke to the alleged victim and the surgeons who supposedly performed the operation to remove the fish from the man's urethra the surgeons even had taken a photo of the alleged specimen when the operation was complete and apparently the dead fish was taken to a laboratory and preserved for study and Jeremy Wade approaches all his cases with skepticism so I doubt he lied about it regardless someone either has their facts mixed up or is outright lying question is who?

  20. Wtf? This is completely false. The candiru does not just suck blood. It bores holes into the flesh and eats it’s victim from the inside out. I’ve literally watched them eat other fish. They are as vicious as piranha.

  21. It is technically possible to find a candiru in a urethra if somebody put it up there himself/herself. Maybe if they were into weird stuff or just wanted attention.

  22. Additionally, the claim about the candiru being attracted to urine was contested by researchers in 2001, as evidence indicates that the candiru hunt by sight and not by smell. Urinating in the water would not attract the fish, and it should not be any more dangerous than swimming in the water!!!

  23. They deadass made a damn video about human parasites years ago, and mentioned the candiru as a parasite on the damn channel. Then they make a video saying it doesnt actually do it. What a joke.

  24. I am sure the people that was victim to getting this fish inside the penis finds this video very useful and comforting.

  25. I'm still not satisfied. A woman can give birth to a baby and looking at my va jay jay I would say no way possible. I just watched the river monsters episode of the man that had the candiru go up his pee hole. Jeremy wade went to talk to the victim, the urologist, and then went to see the actual candiru that's now dead in a jar. It was def bigger than a pee hole but it is very plausible of happening in my eyes. They even showed the instrument they put inside the man to retrieve the lil invader which he was already dead inside the man. Also showed the video from parts of the surgery. So I'm still believing this story. Also the man was in the water when taking a piss. So his junk wasnt far away from the water. Not like he was on the bank of the amazon and the fish had to jump 5 ft up out of the water to make it in him. Sounded more like half an inch is all the lil guy had to jump to get in
    So it didnt swim up a stream of pee as your story is made to believe.
    Idk- all should watch that episode of river monsters and determine yourself what to believe.
    I know down in Ocala Florida, my uncle took us to lake okeechobee in the early 2000s and they had a problem with parasites swimming into humans by any hole. This was a real thing that I saw was a threat due to it already happening. So this amazon story is a very believable story to me.

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