I remember a scene from one of the LotR movies that shows an extreme closeup of Gollum biting into a fish. It's so zoomed in that his mouth takes up the entire frame. The scene is just a few seconds long - all he does is (slowly) bite into a raw fish. I have checked Galadriel's initial "here's what happened in The Hobbit" explanation at the beginning of the first movie, and it only has a wide shot of Gollum from a good distance away.
Of course in the first 3 minutes of the [3rd] movie we see the transisiton of Smeagol to Gollum, it’s bad enough to see Gollum/Smeagol’s face soaked with his drooling but the close-up shot of Gollum eating a live fish made me wana vomit –lotrplaza.com
In my copy RotK, this scene is at 0:5:25