They are found in the new underwater caves, and in the deep ocean. Squids found in caves however, are untameable. PASSIVE TAME!!! 2 people are recommended for taming (one for feeding, one to distract it). It is possible with 1 person, but you'll have to have a creature with very high health.
I tamed one of these and immediately died, of course my reaction was like with most other tames of oh god dammit now it’s gonna die, I zipped over on a dolphin and found it sitting innocently in a ball of about 50 meg carcasses with 2 plesiosaurs in the mix
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
1: The best place to encounter tuso is 90-91 lat and cover all longitude from red ob to the end of herb Island.
2: Don't solo search, make a party and cover full bottom of the map.
3: Don't search in shallow water and surface, go for mid and deep sea.
4: They need to grab your tame then only can they be tamed.(Take Carbonemys with health and speed pumped)
5: They take 50 black pearls per serving.
6: They only agro in deep sea.
7: Last and the most important, the server must be brutal or their chance of spawning is not that much. Put server to brutal and for one day atleast go killingspree in ocean to open spawn spots for tuso.