They can only be tamed with angler gel (you can get it farming achatinas, use a dire wolf or saberthoot). It won't attack you if you're riding a itchyosaurus. It's a easy tame!. After taming they eat fish raw Meat.

But be careful, two of this mf killed my lvl 38 megalodon, and my lvl 18 manta. R.i.p big man.