If you ever swim in the Amazon and Oranoco Rivers of South America please think twice before urinating in the water. Fish called Candiru or Carnero is attracted by urine smell (urea and ammonia) and it can insert it self into the penis or vagina while urinating. Then penis fish lodges itself somewhere in the urinary tract with its spines and it uses its mouth for feeding by sucking the blood. It is almost impossible for fish to survive inside of the human body. Removal of the fish is extremely hard due to the spines and if problem is not treated it can result in removal of the genitals.