"Good answers will result in personal fish fileting and skinning lessons at the next Pond Boss Conference! It could even result in a gift sampler of gourmet products!"
That's enough for me!
You have to file the skin off after freezing the tongue overnight. If you don't have time to freeze the tongue, you can spritz it with kerosene and use sandpaper to wipe off the skin.
That's what my dry cleaner told me, anyways.