Review every lake in the Fish-o-pedia. Monster fish will display at 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 boat around the lake. These fish are identified by a blue dot. The dot will not appear until you get somewhat close to the fish. Use the 80 pound line and the drag set to 1. The fish will eventually get exhausted and can be reeled in easily.