[drfish]

I'm not exactly sure why it seems like it would be more difficult. Maybe the fact that it's a semi-mobile object with (presumably) clearly defined edges moving in front of a background that would "highlight" those edges more so than a static image with assorted textures on it would (sort of a blending effect). Of course, the fish do both already and they look great (however they have more curves than, say, a large leaved plant would)... I guess since I haven't seen moving plants in front of a cycling gradient background and been impressed by it yet I'm thinking it must be more difficult than moving plants (or anemones, soft coral, etc) in front of a static image.

Another thought, if the plants were standing on their own and their movement didn't require a transition between overlaying the gradient and a background it would probably look better (well, be easier to do). I guess I'm just thinking about how I would do it, I'm not nearly as talented as Jim obviously so I see it as a problem myself.