It is tamed in the same way as the Hesperornis, where you have to carry a dead fish to it. Larger fish, and those caught by Ichthyornis, apparently work better. Piranha are better than coelacanths for taming, and salmon are better than piranha.
If you are starter tame an otter it will give you silica peral by killing fish it will give 1 for 1 fish but good for a starter if you didn’t see a silica on the beaches send him to kill and bring silica and it can tame by raw meat or fish meat. Sorry for my bad English but enjoy the silica and otter
These little guys are so much easier to tame in mobile, but harder to find. You still need to kill a megipirahna, but you don’t need to grab its corpse to feed the otter. After harvesting its meat you can easily walk up to it and feed it until it’s tamed. It doesn’t run away in mobile, and I’m sure you can use any fish meat.
On genesis if you teleport arctic north you can find otters on the frozen lake it's a lot easier since they tend to run around on the lake and not swim in the water, they also usually have blue,brown, or black in their color schemes
best to tame a ichthyornis and carry it with you when looking for one of these guys, put the ichthyornis on hunt and retrieve it will catch a fish and bring it back golden and will have a better taming affect to feed to otter, like this up its very important peeps must know :)))