Muskie is the nick name giving to Muskellunge (Esox masquinongy) which name comes from the Ojibwe word "maashkinoozhe" (ugly pike), although some citations refers the name is from the French "masque allongé" (long mask) a modified Ojibwe etymology...

Muskellunge, often simply referred to as muskies, are fast-becoming one of Maine’s premier game fish...