They eat Sweet Vegetable Cakes and you need to tranq them down with darts preferably. Aim for the soft part of the Achatina and not the shell part. Shooting its shell will take more darts to take down.
Guys ,achatina eat berry only with a mod
I think it's krakens better dino you can't feed it berries in vanilla ark be aware! They will require so much cake so better not tame one . hope this was helpfull it's my first time writing a tip •~•