The candiru or "toothpick fish" is parasitic freshwater catfish native to the Amazon and is especially prevalent in and around the confluence of the Rio Negro and Rio Blanco rivers. The term "candiru" is sometimes used in reference to any number of members of the family Trichomycteridae but Vandellia cirrhosa is the most interesting. Candiru habitually target the gills of larger fish to acquire their obligatory feast of blood. Reports of these tiny catfish entering the human body through the urethra date back more than 100 years but the only documented case was in 1997. The man was attacked as he urinated thigh-deep in the river. He required two hours of urological surgery to rid him of the little horned parasite. Ouch! Scientist suspect that the candiru swam up the stream of urine while the urethra was expanded and that the fish would not normally enter the otherwise closed orifice. This little prick could really piss a fellow off!