Review every lake in the Fish-o-pedia. Monster fish will display at the bottom of the lake information. It will list which season and time of day to select when entering the challenges. Monster fish can be found while driving a boat around the lake. A blue dot will identify their location, and will only appear when you get close to the Monster fish. Use the 80 pound line and the drag set to 1. The fish will eventually get exhausted and can be reeled in easily.