This cannot be tamed, but can be harvested for prime fish without killing it. Easiest way to find it is to make several rafts, and dot the open water with them all around the Herbivore Island/wherever you see Leeds. Don't scatter them far across the map, unless you give each names. When one dies, just fly/walk/swim/raft over to the boats, and harvest meat, then kill it.
When I was going to herbivore island I ran into two of these that were right next to each other. I only survived by staying next to the shore, they stay out in open water so doing this is safe. Make this higher for new players