I don't know if I can call it luck but I just found 3 otters lvl 150(yes, all 3) cilling in the swamp near the Redwoods. I managed to tame only 1 'cause of kapros... Btw I am playing ark mobile and i noticed that otters are not tameable in the usuaal mode, with dead fishes,you have to feed them fish meat. I hope that helps and pls vote up so dododex update the taming method for ark mobile
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.
If you are playing on mobile you don't bring it a dead fish instead you have to feed it raw fish meat. Similar to what is done with the diplo or other dinos of that type you just wait for their hungry to reset as indicated above their head and then refeed them.