INTRODUCTION
This tutorial is also brought to you by RMF.GG (this website) which is absolutely amazing, and you should all join it as it's a full community for RPG Maker Developers. Sell your games, buy amazing resources, talk with almost 40k members, and more! Also, feel free to check out my company XyphienLLC.com :)
Now that the self promotion is out of the way, let's jump into that good good.
EASY METHOD:
You can head right over to https://www.rmf.gg/resources/advanced-fishing-system.1699/ and download the Demo with all the working events pre-made. This can save you a lot of time when it comes to making the fishing spots. You'll only need to change a few things whenever you create a new fishing spot.
Once you have the Demo downloaded and you have the game open

Depending on the style of fishing you want there's two options an Easy event (Bottom event), and an Intermediate event (Top event).
The easy event has a single wait phase. You wait 3 silences and then the exclamation will pop up. Every time. If you want an easier system people can time and pay attention to less then this will work for you.
The Intermediate event has thee random times to chose: waiting 1 silence and then an exclamation, 3 silence, and 5 silence. This makes it so it's harder for the player to determine when the fish will pop up, and make it more of random mini game than just a memorization game.
When you've decided the version you want you can simply copy it and paste it over to your game, you do that by clicking on the event once and typing CTRL + C and then clicking where you want the event to go on the new game and clicking CTRL + V. You can also just work from the demo and expand from there. However, if you're pasting it to another game you'll going to have to change the Control Switches and possibly the Variables depending on if you have some used in your game or not. You'll also have to add the items to your game, and change those as well to match.
Now, if you want to create another copy of the fishing event you're going to have to change the control switches as well. To do this follow the following:
Click on the event, type CTRL + C to copy, and then click where you want the new event to go and type CTRL + V to paste. Then you will need to double click the new event so you see this window:
Once you see the window, scroll down until you see your first Control Self Switch, which will look like this:
Click on it, and click space to open it up.

After you're done with that click on the 2 page and then change the selected control switch to the one you just made and changed everything else too.
Next, make sure you copy and paste the bubbles over, once you've done that open up the bubbles event, go to the second event page like you just did and change that switch to the new one.
BAM! You're done! You've successfully finished adding the event to your game!
ADVANCED TUTORIAL:
I'll continue on with this at a later date. This section will explain EVERYTHING in the events, how to replicate it yourself, how to add/change things. Why and how everything works and an entire breakdown of it so you can learn why and how everything works in order to fully teach you about what I did :)CREDITS & EXTRA INFO:
All of this was using the core functions of RM, therefore no credit is needed and this can be used for both free and commercial games as such. Though the idea was mine how to achieve it was not :)
Though if you'd like to support me for this tutorial and help out you can do a few things. Firstly, making an account on RMF.GG, being active, posting, uploading your games, downloading/buying products here versus others helps out immensely! On top of that you're always more than welcome to give me credit for the Fishing system by either adding Xyphien to the credits, RMF.GG, or Xyphien LLC.