Okay I want to clear this up. I am sure most of you already know but there seems to be a little confused on the term non violent tame, It does not mean the creature is not violent it means it is tamed by passively feeding it like a Lystrosaurus instead of knocking it out like a Dodo. For the manta particularly you may be concerned but don’t worry if you are on an Icthyosaurus ( easy to tame at a high enough level there is even a quest that walks you through taming one) they won’t attack you I don’t recommend going anywhere near them without an aquatic mount though. Be forewarned however they are only tamed by a fairly rare substance called angler gel so keep playing to find some I would check here on Dododex for creatures that drop it (other than anglerfish of course that one is pretty implied)