Once I got home with today's images I couldn't get over how much this leaf floating on the surface of a nearby lake looked just like a fish half out of water.
Canon 40D, EF 70-200mm f4L USM
F14 @ 1/250th, ISO 320
Manual Mode, Pattern Metering
Handheld, Natural sunlight
Processed in ACR & CS4: Small crop, levels and curves adjustment
If I "browser-crop" to eliminate the brown reflection above the leaf, I see a bird in flight.:)
The leaf itself is interesting, and the near-complementary colors are good, but it's a bit small in the frame for my taste. The EXIF (after saving your image locally) tells me you were at 200mm, so I guess getting closer wasn't an option, short of swimming.:)
Chris is right. It does look like a bird-in-flight. I also think he hit all the points. Bigger in the frame would be better but you can only do what you can do.
A 400 would be nice. Have you tried a 1.4x TC with your 70-200? I have used a Kenko 1.4x TC with my 70-200mm f/2.8 and that extra 80mm does help. Just a thought.