I changed the flyfishing a little.

You will not need to spin or anything and still catch fish. This means you can put your flyfishing rig into a stand and it will still catch something eventually (depending on the bait of course).

You need the Unity Mod Manager from here:
https://www.nexusmods.com/site/mods/21

Then install my mod from here:
https://www.nexusmods.com/ultimatefishingsimulator/mods/1

Start the game and make sure the mod is "green" (enabled).

p.s. Not sure, but I guess it is best to have the game installed into: C:\GOG Games\

pps. before you update the game, open Unity Mod Manager and uninstall -> update the game -> install