Here is the fish animation. I did it one year ago when i was a complete noob with maya, I mean, more noob than now.
The problem with it is that one side of the fish is not lighted at all, but looking nice to me i left it there and began learning other things.
The plants are not modelled, are paint strokes converted to polys so that can be rendered in mental ray.
Another thing is that the fish is following a curve and the start and end points are the same, so the player can be looped without discontinuity in the fish movement.
view fish animation
download fish animation
Tomorrow I hope to have 10 seconds of the sea animation and post it alone without the fish.