The Candiru!

I spent a few weeks in the Ecuadorian Amazon several years ago, and although we were told it was okay to swim in the river (and we did quite a lot, often drifting downstream for hours, surrounded by enormous blue morpho butterflies, with occasional lines of parrots winging overhead...), our guide said to get out of the water if we had to pee, or if we got a cut. I knew before this trip that piranhas would go after blood in the water, but had no idea that the candirú was a threat as well. Although my guide did not mention the name of the fish, it was pretty clear from his presentation that he viewed the candirú as a much greater threat than the piranha (which only eats you alive).

Hyla