A strange example of mutualism has surfaced at a hot springs in Turkey where, for a fee, you can be bitten and attacked by hordes of tiny fish.
The fish, a very rare species that are known as "the doctor fish of Kangal," fill the 34 degree Celsius water (93 F) to the almost complete absence of other plant or animal life, swarming humans as soon as they appear.
The fish's name comes from its legendary curative abilities, due to the fact that it has been documented to relieve the symptoms of psoriasis, a skin disease triggered by stress, by eating away layers of dead skin as the patient relaxes in the hot spring environment, and stimulating new growth.
The mutualism arises from the fact that the fish have little else, besides human skin, to feed off of. Apparently, locals sealed off the spring from surrounding creeks in the 1950s, to preserve the "miracle fish" that were known to have healed injured people. Consequently, the fish have grown dependent on humans for food.
Apparently, Chinese and Japanese companies have already built resorts containing "doctor fish" trained to eat dead skin.
Surely, it is only a matter of time before such "fish pedicures" come to America.