Thank you for the reply and the feedback! I don't have a widescreen myself, so the issue did slip through the cracks. I'll make sure to pay greater attention to that in the future.
I need to add that you can control most of the game using keyboard, including selecting fish via number keys in all menus. The only thing you need the mouse for is the Main Menu, Proceed/Reset/Give Up in the Day Menu, and Price changing.