Perham (pronunciation: /pɜrəm/ pur-əm) is a city in Otter Tail County, Minnesota, United States. The population was 2,985 at the 2010 census. The town hosts The Gathering (show), described as the world's largest fish decoy show.. The annual event will be in its 13th year when it is held April 17 and 18 of 2010.