Candiru - the notorious blood-feeding catfish
The candiru (pronounced "candy roo") is a tiny catfish (several of them actually) that inhabits the waters of the Amazon and
More feared then the piranha; Vendellia cirrhossa and its relatives are tiny vampires that typically parasitizes other fish by attaching themselves to their host's gills before gorging on their blood.
The candiru’s fearsome and gruesome reputation, however, stems from its reputed habit of following the scent of urine and entering the urethra of an unsuspecting human victim. After entering the penis or vagina, the candiru heads “upstream” then secures itself in place with clusters of hook-like spines situated on its head. As the candiru feeds, its body expands causing excruciating pain. Surgery or amputation (for male victims) is required to remove the fish - that some refer to as only known vertebrate to parasitize humans (while others consider it a blood predator and not parasite). According to folklore, the candiru is said to be capable of following a stream of urine to its source (like some tiny, x-rated salmon), even if the person relieving himself is standing on a riverbank.
So what are the facts about the candiru? Is it really a dangerous parasite? And is the vampire catfish even attracted to urine? If so, can it swim up a urine stream? What are the odds that you'll be attacked by one if you swim (and/or urinate) in water inhabited by the candiru? Some experts believe that the fish may actually be homing-in on something else (like ammonia or even the electrical currents produced by muscle contractions)? Leading researchers are still figuring this out.
Read Dark Banquet: Blood and the Curious Lives of Blood-Feeding Creatures to find out more about the candiru - maybe more than you want to know. Additionally, readers should pick up Candiru: Life and Legend of the Bloodsucking Catfishes, an extremely informative and entertaining book by Dr. Stephen Spotte, who lent his considerable expertise to the candiru chapter ("Candiru - with a Capital C and that Rhymes with P") in Dark Banquet.
More feared then the piranha, the candiru is actually a tiny subfamily of catfishes that inhabits the murky waters of the Amazon and