At such a spa, many Garra Rufa, a type of small tropical undefined undefined undefined undefined undefined undefined undefined undefinedfish, also nicknamed Chinchin Yu, nibble fish or simply doctor fish, are put in hot springs. As they can live and swim freely in at least 43-degree-hot waters, they are naturally used for the treatment of skin diseases in such spas.

When placed in the spa, these fish can feed themselves on the dead cells of the human body, since they only consume such cells, leaving the healthy skin of the human body to grow. The whole process is reportedly free of pain. It won't hurt and the bather might feel a pleasant tingling on his or her skin.

The fish species are often found in the river basins in the Middle East, including Syria, Iraq, Iran and Turkey, and thus is also called Turkish Fish. It is legally protected from commercial exploitation in Turkey due to concerns over harvesting for export.

In 2006, the first Asian Doctor Fish spa resort opened in Hakone, Japan. These fish are used to clean the feet of the bathers at the spa. Recently, such spas become fashionable in resorts in China and South Korea.