"Monster Fish" do not necessarily mean they are large, but they are extremely rare, in all but one case extinct. Most are actually under a foot. Some of these fish are some of the smallest fish in the game, and some are the biggest fish in the game. These fish are the most valuable fish in the game, with the exception of the Rolfosteus Canningensis. These fish may take real life days to catch, but may only take a couple hours.