Chummy Fix allows you to fix the odds of a drop appearing in your farm’s fish pond(s). You can only produce valid items based on the fish in the pond.
Install the latest version of SMAPI.
Download this mod and unzip it into Stardew Valley/Mods.
Run the game using SMAPI.
Once you have followed the installation steps above and started the game once, you will see a new file in the mod folder called config.json. Edit the config file in a text editor like Notepad to change the probability of an item spawning in your Pond’s chum bucket. Values are a percentage between 0 and 100.