Now THAT'S what I call an informative post. I can't believe you almost didn't post this, especially given its relevance!

I watched Finding Nemo 3 or 4 times this weekend. (My son has the stomach flu so we spent most of the weekend on the couch.) Pixar did a ton of research on this film. All the animators were 'forced' to get scuba certified as part of their research. I can imagine they also placed microphones into fish tanks and tapped on the glass to research that scene.