Automatic fish farming involves right-clicking a door with tripwire above it and hoppers for collection. It’s a good idea to use an automatic fishing rod dropper to supply new fishing rods when the previous one breaks. The ideal rod is Lure 3, Luck of the Sea 3, Unbreaking 3 and Mending. Apply a rubber band over the right mouse button to make the experience truly afk. If playing on Ps4, You may want to jam a coin in between R1 and R2.
Note: None of these work in Bedrock Edition, due to how tripwires and doors work. Mojang also does not want to allow AFK fishing in Bedrock Edition. As such, most AFK fishing designs involve exploiting bugs that get fixed in the next update."