(Note that this is exclusive to the No Untameables mod for ASE and ASA)

In order to obtain a tamed leedsy you will need to knock out a wild one. I suggest having a tranq mod as a leedsy loses torpor fast (usually for me waking in 1-2 minutes). Once it is asleep approach it and access its inventory. If you are lucky the leedsy may have a fertilized egg. That egg can then be hatched to get your own.

More Leedsichthys Taming & KO Tips