Thank you to all participants for your high-quality entries!
My general take on the entries was that I preferred color to B&W, and I liked seeing increased detail on the body of the swan without increasing the local contrast in the rest of the scene. I liked seeing a slight increase in the exposure of the water and carp, but didn't like seeing more saturation (the koi seem vivid enough without any extra help). I noted nice touches, like moving koi or reducing their count, straightening up the swan, and lightening the neck of the swan while bringing down the body exposure a bit to increase the visible detail. So, the results:
Winner: @Kae1 #1 (color). Ticked nearly every box for me. I liked the thoughtful culling of the koi.
1st Runner-Up: @frankmulder #1. I enjoyed the cooler color shift and the light hand on saturation.
2nd Runner-Up: @Hendrik . The soft detail in the water was perhaps the best.