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 Orinoco River basins in South America


                                                                                                      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.

             Catfish and swimmer attract some nasty companions - a school of candiru


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.


                                     Candiru swimming upstream


   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.

Candiru attacking peacock bass

   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 Orinoco River basins of South America. Typically, candiru feed on blood from other fishes (after attaching themselves to their gills with tooth-like odontodes) but on rare occasions candiru have become lodged in the human urethra. The reasons for this behavior are explored in Bill Schutt's book, Dark Banquet.