Topic category: User side tutorials
This is an easy tutorial, all that is need is 1 big procedure and an item tag or a percent chance procedure. First you should make the tag or chance procedure which will be used to grab from a pool of loot to spawn instead of whatever would normally be fished. The easier option is a tag, so this is what that would look like:
In this tutorial I will not demonstrating how to make the other option, but you basically you would call a procedure which gives different items based on a chance instead of grabbing a random item from the tag. The result of a procedure instead would give the ability to make items more or less common. Moving on to the procedure, here is an image of it.
The dimension and biome can of course be customized to use one or both with any available options. Last thing to customize is the text input in the "random item from tag" block, put in "(the_name_of_your_mod):fishing_loot_table", which is the tag you created before this step. You will also need to make 6 global variables as well, the x y and z velocities, and the x y and z positions. Make them number types and player persistent.
And that is it! My methodology may look weird, but I was testing many different ways of removing the original object for days, but since this works, it works!