Candiru

Candiru (English and Portuguese) or candirú (Spanish), also known as cañero or toothpick fish, are a number of genera of parasitic freshwater catfish in the family Trichomycteridae; all are native to the Amazon River. Although some candiru species have been known to grow to a size of 16 inches (~41 cm) in length, others are considerably smaller. These smaller species are known for an alleged tendency to invade and parasitize the human urethra; however, despite ethnological reports dating back to the late 19th century, the first documented case of a candiru parasitizing a human did not occur until 1997.