Name an animal you might worry about if you were swimming in the amazon?

PIRANHAS!

Another scary critter in the Amazon river is the Candiru(English and Portugese) or candirú (Spanish), also known as cañero or toothpick fish. They are a type of parasitic freshwater catfish 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 where the allegedly swim up it and then deploy barbs to prevent their removal. Despite reports dating back to the late 19th century, the first documented case of a candiru parasitizing a human did not occur until 1997.