In this guide, you will find out how to fish in Lost Ark.
You cannot fish until you unlock crafting from the main storyline. You will need a fishing rod equipped to fish, then press the B button to go to the crafting menu. You have to point your cursor towards the water where you see the fish. You have to press the button with the fishing pole equipped, and you will cast the fish out of the water, as shown in the image below.
When the fish bites, you need to press the same button to reel it in. You can also unlock the fish trap when you progress fishing in the main storyline.