In Monster Hunter World you can go fishing. However, the game does not do a great job at explaining this side activity. After the prologue you automatically unlock a Fishing Rod. It’s a fixed item in your inventory.
Start by going on an expedition and look for a pool of water. You can find water easily on the map. You may also want to check out beaches if there are any. The “Ancient Forest” map, “Southwest Camp (1)” is good for a start. It has a small lake to the east of the camp where there are many fishes. Some maps even have a Piscine Researcher marked on the map who has a fishing quest for you.
Once you’ve found water with fishes swimming inside, equip the Fishing Rod and aim it at the water. Press / with the rod in hand to start fishing. The fake food is good enough to make a catch. Once a fish bites, you must press / to reel it in. You’ll know the time is right when the fake food starts moving around in the water, this indicates a fish is biting it.
Small fish are easy to catch. Bigger and rarer fish require you to complete QTE button events.
What Fishing is good for:
It’s mostly for completing delivery requests. These can unlock fantastic rewards in Astera such as better fertilizers for the botanist or new food for the canteen. The fish loot you get can provide good buffs and some of it is used in crafting. For example, the “Burst Arowana Scale” is used to make large amounts of level 2 gunpowder.
The Piscine Researchers who are randomly spawning on different maps also give you quests for catching certain fish.
There’s also a trophy / achievement called “Angling for a Bite” which is for catching your first fish!