According to Pixar, animating "Finding Nemo" was tougher to animate than any of the previous films tackled. Visits to aquariums, diving stints in Monterey and Hawaii, study sessions in front of Pixar’s well-stocked 25-gallon fish tank, and a series of in-house lectures from an ichthyologist all helped to get them to produce the animations that caricatured reality.

Supervising animator Dylan Brown, an eight-year Pixar veteran, and directing animators Mark Walsh and Alan Barillaro were responsible for guiding an animation team that fluctuated between 28 and 50. With characters ranged in size from a cleaner shrimp to a blue whale, the animation team had to learn about fish locomotion and how to create believable behaviours for characters without arms or legs.

Dylan Brown (Supervising Animator): “Each film has its own unique set of challenges and we always begin by trying to figure out what they are and how to solve them. With ‘Nemo,’ we had an entire cast of fish characters with no arms or legs. Since they didn’t have the traditional limbs to allow strong silhouettes, we had to invent a whole new bag of tricks. In the beginning it was a bit daunting and frustrating. We began analyzing what was appealing in terms of posing fish. We put a lot of work into the face and getting the facial articulation just right. We didn’t want them to be just heads on sticks like in a Monty Python sketch. Their faces had to be integrated with the entire body language. Where a human character might just turn his head to look at something, a fish might turn his head just a little and the entire body would pivot along with it.

“Another big factor for us was timing. With characters like Buzz, Woody or Sulley, you have an earth-based gravity. But fish underwater can travel three feet in a flash. You blink and the thing is gone. We were wondering how they did that and studied their movements on video. By slowing things down, we could figure it out. Our timing got very crisp as we learned how to get our fish characters from one place to another in the course of a frame or two. We always tried to incorporate naturalistic fish movements into the acting. By putting things like one-frame darting and transitioning from one place to another into our acting, the characters became very believable.“

Alan Barillaro (Directing Animator): “It became fun and challenging to come up with a whole new range of how to communicate and gesture. You don’t have gravity to deal with underwater, so we discovered things like when a character gestured, he would tend to drift a bit more. I found that a lot of the gestures humans make could be boiled down to eye and face movements. I would look at my own face in the mirror and imagine I had a tail on the back of it.“

Mark Walsh (Directing Animator): “The first thing that Andrew did on the film was to sit with us in front of the fish tank and basically pitch the story to us. He explained that the magic of the world was going down to the perspective of a clown fish and imagining him going through an entire ocean and encountering sharks, turtles, jellyfish, etc. You imagine moving in closer and seeing this little fish and how hard he is trying.“

To ensure that their characters would have the range of expressions and movements needed, the lead animators linked up with modelers and riggers from the character department and served as their “animation buddy.“ With direct input from the animators, the technical directors created new and improved tools and controls (known as avars) to enhance the overall character performance.

Brian Green (CG Character Supervisor): “This was the first time that Pixar has had a character department and it allowed us to serve the animators’ needs better. The animation buddy might give us a drawing and say ‘For acting purposes, I need it to look more like this.’ We would go in and adjust it. This made for a very close relationship. We also tried to create automatic dynamic motion for some of the characters. Our goal was to try and automate everything we could – things like the movement of dangly bits on some characters – so the animator could concentrate on the performance.“