Fishtail was named for Mr. Fishtail, a local resident. The first post office was established in 1901 with Charles Sullivan as postmaster. The mail route consisted of service for the Fiddler, Fishtail and Rock Creek areas. The first store was built by Stressley Tunnell who later served as postmaster. In 1908, Benny Banks bought the store from Mr. Tunnell, and soon after, additional buildings such as a saloon, blacksmith shop, hotel, and livery barn were added to the town.
Fishtail is located in south-central Montana, 25 miles southwest of Columbus on Montana Highway 78.