Im not trading but if look up the spawn map for ragnarok in the SW there are two small ponds next to each other. Look in there, if there are no otters then kill the fish and look in 2 hours. Thats where I got all of mine.
I'm in single player and can't find one after a couple days trying and destroy wild dinos command. I'll try the killing the fish trick though, haven't thought of that.