You can get this achievement early in the game.
The first pond with fishes you'll run into is at:
Ancient Forest > North side of Section 1N.B. You will find an NPC named "Piscine Researcher" near the Ancient Forest pond. Talk to him and he'll give you a critical bounty to complete: catch a fish in the nearby pond (you don't say).
You already have a fishing rod in your base equipment, so select it with
and follow the on screen tutorial.
Basically, you have to aim at a bank of fishes, throw the line with
and press
when a fish bites. Hooray! You caught your first fish!
Warning! Be sure the controller's vibration is enabled, since you'll get your
screen alert only during your first catch. After your first fishing, pay attention at the vibration: that's the exact moment to rapidly press
and catch the fish. The only exception are large fihes: if you catch a "big" one, you'll have to play a quick time event in order to capture it.
Warning (2)! If the fishes aren't biting your bait, press
to slightly move it and get their attention.