Fishtail is a small unincorporated community in Stillwater County, Montana, United States. It is located on the West Rosebud River. Well known locations include the Cowboy Bar, Potter's Rock Shop and Coffee House, and the Fishtail General Store, founded in 1900. Its post office was established on February 15, 1901 with Charles Sullivan as its first postmaster. It has a zip code of 59028.