Nier Replicant Ver 1.22 is a redesigned version of the original Nier Replicant, which was released exclusively in Japan in 2011. The visual effects and soundtrack for this version have been redesigned and many changes and improvements have been made to the gameplay. In the original title, fishing is a fun little distracting game, and it remains the same in the 2021 release.
If you want to catch all the fish in the game, you must find a giant catfish in Nier Replicant. This is where you should go, what bait to use, and how to fish successfully in general.
Giant catfish can be caught in the river that runs along Dongfang Road. You will need to use the carp as bait, and the land as bait can be caught from the water with the water wheel at home. Once you have some carp, go to the river on the east side of the road and press Circle / B to remove the fishing line.
The giant catfish is a bit more difficult to catch than the other fish in Nier Replicant, because you need to pull the line in the first small mouth instead of leaving more room with other people like before. Once you see the rod bend, press Circle / B to start winding it.
From this point on, being involved in the giant catfish is the same as being involved in any other fist. Pull the fishing rod in the opposite direction to move it and reduce its HP to zero. After the HP is completely depleted, you can enter the giant catfish.