The challenge to catch a Whopper in Monster Hunter Wilds as part of Kanya's quest, The Catch of a Lifetime, is a funny one. Unlike the other fishing sidequests in MH Wilds, this one gives you a choice of which fish to catch,

In Monster Hunter Wilds Goldenfish can be found in caves and areas with calm water away from direct sunlight in Windward Plains, Scarlet Forest, Oilwell Basin and Iceshard Cliffs. We also found that switching the season to the season of Plenty significantly increased the spawn rates of Goldenfish.