Candiru, The Amazon's Most Feared Fish

Maximum Length: Up to 6 inches
The Amazon's Most Feared Fish: The Candiru is a terrifying fish, even when stacked up against its fellow river monsters of the Amazon. But this parasitic freshwater catfish does not instill fear by way of its monstrous size. On the contrary, it's small, eel-like and so translucent that it can be nearly impossible to spot in the water, which makes it even more terrifying. Some claim this fish is the most feared in the entire Amazon region, and the fear stems from the fact that it has a knack for finding open orifices and working its way inside. Once inside another organism, the Candiru feeds on its host's blood, becoming increasingly swollen. The Candiru is the star of an urban legend — which turns out to be true — of a man who was urinating in the Amazon River when a 6-inch Candiru swam up his urine stream into his penis. The fish remained there for days, until a surgeon was able to remove it. The Most Horrific Candiru: Perhaps the most horrifying Candiru species of all is the Candiru asu. This small catfish is a voracious parasite. It uses its circular mouth and sharp teeth to bite flesh and then enter organisms, leaving behind a wound that looks uncannily like a bullet hole. The Candiru asu proceeds to feed on the organs, literally eating its victim from inside. Human corpses have been discovered in the Amazon filled with more than 100 of these river monsters. Scientists and coroners have determined that the victims may have even been alive and simply incapacitated when the Candiru asu struck. In Jeremy Wade's Words: "The candiru usually targets a big fish as its host, drinking blood from its gills, but occasionally they make mistakes. This has resulted in one of the most infamous legends to emerge from the Amazon: a man urinating in the river who has a fish swim up his penis."