Best way make a water pin using wood pillars start on the beach from shore to sea make sure when building pen to have 7 feet deep pillars in water and above water surface 2 feet pillars the manta can escape over. When pillars meet land have them between water ending point to land so manta doesn't get killed while being out of the water. to lure them in use baryonyx to knock them out while they are in pin with tail spin. Then close gate. When the mata reawakes lure it to the corner of your pin and place pillars around it will be stuck easy taming then feed angler gel becaerfull when its yours to whistle stop then put saddle on if not it will follow you and risk itself of killing itself
They have terrible turning circle, approach one from above and feed it. Then let it swim circles around you. The occasional time it gets close you can predict its attacks, it “bucks” just before the attack, which is the tail swinging underneath. Quick swim up or back avoids it. Be prepared to get dizzy, long time between feeding
Tame a kaprosuchos and swim to one of these bad boys and do it's alternate attack it will grab it in it's mouth. walk onto the shore where its safe and have another person feed it while in the gators mouth (if you unmount it drops it) it wont attack or die because it's technically not on the shore.