Fun action shot, Allen. I can't quite tell but it looks like a gizzard or threadfin shad from the rear. You make some great images with the 40D/300-4 combo. I use that same combo sometimes when my shoulder is aching and I'm always pleased with the results.
Very nice whites and action captured (pun intended :))
Wish for the wings to be on the up or down position, more attractive than half-way.
Sharp and nicely presented.