The Fisher River is a tributary of the Kootenay River in the U.S. state of Montana. The Fisher River properly begins at the confluence of its two main tributaries, the Pleasant Valley Fisher River and the Silver Butte Fisher River. Of the two tributaries, the Pleasant Valley Fisher River is the larger and is sometimes considered part of the Fisher River proper. A variant name of the Fisher River is Pleasant Valley River, and a variant name of the Pleasant Valley Fisher River is Fisher River.