Update #5
A small update this time, just to let you know that I've uploaded a new version of the game with the new things present in the 4th update, and that i've rebalanced the fishing area upgrade system. Now the shells needed to upgrade, and the consequent value of the fishes, automatically scale with the buy order. The fishes all start at the same price, in this way the player can buy the ones that finds more interesting first, and then buy the others to earn more shells.