On crystal isles you can commonly find these guys near the shore with the text "does not want to be tamed right now". Dont fall for it,you can still tame it but its gonna a lot weirder than if it was completely underwater. First if you hit it with your tame (e.g carbonemys) riding or watching far away commanding it to attack it will stay still and not attack and afterwards it will be completely passive even if you attack it. First you need to get your tame close to the tuso (dont worry it wont aggro to you first), then attack and quickly run away. This way even though it normally wouldnt have wanted to grab your tame will still grab it since it is the nearest dino there is,afterwards feed it black pearls or cooked prime meat if you wanna go for a few more rounds. It wont do that much dmg to your tame if you feed it quickly,like not even 500 dmg.