You will need a turtle that has more health than agiga, no joke, you need 150 kibble tame turtle with all levels into health and reason for high level because it constantly gives your turtle a higher torpor which will then knock it out and then let go of your turtle, when you have that you go to its mouth and feed it black pearls, you may need more than 1 turtle
Use a Mosa to tame this beast. Let the Mosa get grabbed wait a couple seconds get off feed it black pearls. Have your mosa on follow lowest, swim a bit away from the Tuso after feeding it, when the Tuso lets go the Mosa will swim to you. Repeat until Tuso it tamed. Super easy!
You need two people, one for feeding the black pearls and the other to feed the turtle that is in the grasp of the Tusoteuthis, with sweet vegetable cake for the health and to feed it stimulates berries as well