As everyone else has said, this is a lovely piece! What I enjoyed reading in the comments are those who are responding with the feelings this image evokes for them. I read keywords like "quietness", "loneliness" "sense of dread" "emptiness". BTW, I totally agree. I get all that from this image.
Now, the question is -- are those the feelings you intended to evoke? If so, excellent! Sit back, pop open a soda and binge watch the new season of Trollhunters this weekend!
If not, then there's work still to do.
You didn't mention it in your original post, so I just want to ask: have you identified your intent for this piece? How do you want the viewer to feel? What do you want them to look at first, second and (if applicable) third? When you can communicate your keywords all sorts of things start of fall into place. Not only for you, but also for your peers who offer critiques.
For example, you absolutely can add fish or ducks to this piece. It will still be a very nicely executed image. BUT will the addition of those element reinforce the way you want the viewer to feel? Or would you just be adding "stuff" to an image that is already working splendidly?