THE SUN: A FISH swam the wrong way when it leapt upstream into a boy’s PENIS and ended up in his BLADDER. The first, and most dubious aspect of this story is the victim’s account of the candiru swimming up the flowing stream of urine. In order to swim up a stream of urine, the fish would have to be narrower than the stream in question (as it would have to have a medium to push off of) and working damn hard. Well, according to legend, that’s what the Candiru is capable of. According to the myth, the Candiru will swim up the urination stream and embed itself several inches inside the urethra. One of the strangest [stories from the Amazon concerned] a fish that was urinophilic and could swim up the urethra or into the vagina of the unwary native who urinated while bathing in the Amazon. Supposedly, the fish mistakes urine for water expelled from the gills of marine life. Urine is generally warmer than river water, and our urine “smells” (fish don’t really smell, rather they have a sense of “taste”) delicious to them, so up the human urine stream Candiru fish swims! There are further problems with this case, including the candiru that was supposedly extracted. In other words, once the source of the smell is located, it is said that the fish swims up through the stream of urine coming from the urethra and heads into the organism’s urinary tract. This, of course, not part of the fish's normal feeding behaviour - the fish has made a fatal mistake. After tasting the urine the candiru may follow the urine stream back to the human. So they swim UP the urine stream the human (male OR female) emits in the water. To the extreme agony of the unlucky person, the Candiru swims up… into their genitals. It is however one of the most enduring myths of the candiru’s behaviour. Obviously this is not a big fish, but why would any fish even want to do this? The Candiru fish (Vandellia cirrhosa) is a small catfish purported to enter the, ahem, intimate orifices of unfortunate people who urinate into Amazonian waterways. Here’s a description from a 1973 article in Urology by John Herman:. Once up the urethra the fish can not turn nor can it move backwards because of the rear-pointing spines on its gill covers. https://www.animalplanet.com/.../videos/fan-favorite-fish-swims-up-urine-stream It then swims up the urethra and uses its spines to manifest itself somewhere in the urinary tract. We will get to that later. The candiru may swim up the stream of urine and enter the urethra of a bather urinating into the river. However, some live in other places too. Cecil replies: Can’t blame you for your skepticism — this is one of those stories you want desperately not to believe. Dr. Samad claimed that he had to break the spines of the candiru to extract the fish. While there are several variations of this myth, most of … The 2cm daredevil caused all kinds of medical problems when it swam through the teenager’s urethra. It is locked in. First up on the list of fish that swim upstream is the salmon, it’s also likely the first upstream swimming fish that comes to people’s minds. The problem is that basic laws of physics along with the anatomy of the candiru preclude this fish from jumping up a stream of urine into a urethra. The unfortunate lad was taken to hospital with complaints of pain, dribbling urine and acute urinary retention. The most common type of Salmon, the Atlantic Salmon, can be seen primarily on the West Coast in the Pacific. The fish is attracted by the smell of human urine. In reality, extensive research has indicated that much of this legend is probably a myth since Candirus detect the gills of fish by sight more than scent and the physics of fluid dynamics makes it impossible for then to swim up a stream of urine. This is beyond far-fetched and for all intents and purposes impossible – the laws of fluid dynamics do not allow it.