This creature is so easy to tame. All you need is:
1. An Ichthyosaurus(these guy won't be attack by any water creature, except the jellyfish)
2. Anykind of meat(I suggest using prime meat and don't use fish meat)
3. Find one of these creature
4. Feed it prime meat(It's a long time between the 1st and the 2nd feed, after the 2nd feed it's fast)
And then you get one of these, just be careful of the megalodons, they will attack right after it is tamed. I hope this is useful for you<3

Dodex fix your stuff takes like 5 mins for hungry again

Don’t actually knock it out its a passive tame. Mine took around 23 meat and 15 minutes for a lvl 70 basil, totally worth it.

Fun fact: the first time you feed it, it takes a while. The rest of the time, it’s much faster, don’t worry!

I got lucky and was able to find one of these things without mantas near it in the shallows of Herbivire Island...thank goodness, do not use fish meat!!