My apologies, I totally just realized I made a mistake in the instructions for the fishing minigame. You're supposed to use A and D to move the hook, not the arrow keys. When a fish bites the hook, mash the left mouse button, while holding down either A or D (whichever one is opposite the direction that the fish is moving). Each time you click LMB, the fish will move ever so slightly closer to the top of the screen, and once it's out of the water, you will have won the level.
The idea for this game is to have around 10-15 different game modes (I've got a few more planned besides the ones already in the game), each with a whole bunch of levels.
Thank you for playing!