A story in the Metro tells of a man who went for a rejuvenating spa treatment that involved swimming among eels--and found one of them entering his penis. He was unable to stop its ascent and had to have an operation. Surgeons removed the fish, already dead, from his bladder.
Where to begin? First of all, this sort of treatment is not as odd as it may sound to the Western reader. A Mesopotamian carp called the reddish log sucker or doctor fish (Garra rufa) is often used as a treatment for psoriasis, eczema, and other skin problems. These fish normally feed on algae and other organisms that coat rocks submerged in water. When a patient immerses himself in a pool populated with them, they treat him as an algae-coated surface and go to work removing the dead skin, leaving the healthy, living parts unharmed. It is said that the doctor fish "eat" the dead skin, but apparently what they're doing is more like pulling it off in a futile search for food.
This medical treatment has also been used for merely cosmetic exfoliation. In a Youtube video with commentary too annoying to stream here, a man undergoing a fish pedicure claims it feels like electric current going through his feet.
Here's a video showing the use of doctor fish to treat psoriasis:
But back to our Chinese penis case. The fish used there weren't doctor fish, but, according to the story, some sort of eel. I wonder, though, if this errant one at least might really be a catfish. In South America, there are pencil catfishes, including the candiru, that live by swimming into the gills of other fish, anchoring themselves with spikes, and siphoning off some blood. They're like fleas feeding on mammals. Occasionally, as described in The Book of Deadly Animals, one of these pencil catfish mistakes the scent of human urine for the waste products exuded through a fish's gills. The pencil catfish then swims up the human urethra, to the discomfort of both parties. Before modern surgery, some people died, or lost important parts and wished they had died, because of these invasions of privacy.
Thanks to Croconut for the news tip.