Den, Nice duck, nice water. I am unable to comment on colour, but feel you could get more colour and detail out of the dark head? If this image were mine, I would consider darkening the reflection a little and lightening the back where the solid black is. The black looks a little choked and heavy. One minor nit is the small, darkest reflected bit of water on the LHS...it really draws my eye for some reason.
Nice water and a pleasant reflection. I agree with Glennie about wanting more detail in the darks. At ISO 400 you should be able to pull out more unless it was underexposed. If he had turned a little toward the viewer it would engage the viewer more compellingly and would put more light on the face. It is quite shaded as is.
I don't know the duck that well but wonder if the light feathers on the side have gone a bit too gray.
I don't know how much you cropped but I would take a little off the top and add it back to the bottom, and add a little on the right.