Your game was fun! Here are a couple tips / suggestions.
I would make it so the player can manually pick up trash in the beginning. This will allow the player to earn coins in the start quickly instead of having to wait for the 1 fish. Think of the game cookie clicker. The player can manually click the cookie to get 10,000 cookies but the real goal is to buy cookie automation upgrades so it does it for you!
Another tip is to allow for resizing of the gameplay window. This will allow people on many different monitor setups to enjoy your game.
I really enjoyed the game and the tutorial was a great as well! It really helped!! Great Job!