After reviewing 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 are found while driving the boat around the lake and are identified by a blue dot. The dot will appear when you get close to the fish. Use the 80 pound line and the drag set to 1. The fish will eventually become exhausted and can be reeled in easily.