Of all of the beasts that prowl the Amazon, none is more ꜰᴇᴀʀᴇᴅ by the locals than the candiru. A river monster ꜰᴇᴀʀᴇᴅ even above the dreaded piranha; the candiru waits for its unsuspecting prey to step into the river before latching onto it.
Candiru (Vandellia cirrhosa), also known as cañero, toothpick fish, or vampire fish, is a species of parasitic freshwater catfish in the family Trichomycteridae native to the Amazon Basin where it is found in the countries of Bolivia, Brazil, Colombia, Ecuador, and Peru.
It’s also only about an inch and a half long, though don’t mistake its small size for weakness. This little fishy packs a ᴘᴜɴᴄʜ. Described as “very small, but uniquely occupied in doing evil,” the candiru favors a more stealthy approach than its ꜰʟᴇsʜ-ᴇᴀᴛɪɴɢ counterpart. Rather than go for an outward ᴀᴛᴛᴀᴄᴋ, the candiru implants itself inside the human body through a rather unusual entryway – the human penis.
The fish swims up the penis into the urethra – upstream, which is an impressive feat for such a small fish – where it latches onto the walls with barbs. Removal can be very difficult, as the barbs face one direction only, and pulling on the fish only causes them to sink deeper into the walls of the urethra.
Even more ꜰʀɪɢʜᴛᴇɴɪɴɢ than the prospect of a tiny fish making your penis its home, is the prospect of getting it out. Here, it permanently lodges itself to feed on ʙʟᴏᴏᴅ. The worst, the candiru will stay lodged in the organism until it is sᴜʀɢɪᴄᴀʟʟʏ ʀᴇᴍᴏᴠᴇᴅ, as the urethra is too small to allow the fish to turn around and swim out, and the head spines prevent forcible removal. A few native people suggest home remedies like a hot bath or an herbal soak, but for the most part, the verdict is a unanimous and ʜᴏʀʀɪꜰʏɪɴɢ one: complete removal of the “offending appendage” altogether.
It’s been said that the candiru ʜᴜɴᴛ by smell. And the smell that attracts them the most? Urine. Local residents, and even some websites, spread the belief that after this fish smells urine in the water, it swims toward and then up the urethra. Then, the parasite supposedly lives inside the urinary tract of this unwilling host.
Although there are a number of individuals who claim to have first hand experience with such events, these tales ultimately lack the evidence necessary to prove that this fish actually does swim up the urethra (there are no videos, no images, and no victims—just story tellers who claim that they were there).
So as it stands, the stories about the fish swimming up a human’s (or any organism’s) urethra are unsubstantiated. However, many people continue to believe that, if you are submerged, your urethra is a potential target. Native men along the river have long been known to tie strings around their penis to prevent such things from happening to them while going into the river. Other tribes have been observed wearing various forms of makeshift protection to cover their genital areas while bathing.