i am imagining you took this shot at high iso which explain the noise, i'm not sure if you tried to neat image it , this would really help with the noise.
which in turn will help you to higher the contrast on the fish,basically probably pushing your score higher, from what i've seen int he comments.
What's the matter with the voters (or what's the matter with me)? I gave this a 9. I don't care if it tells a story, or shows the environment, it a beautiful picture of a very interesting fish. I like the shadows, highlights, and colors. Phooey to the rest of them!
Your title implies this is not in an aquarium, if so then I'm seriously impressed! I just wished you pumped up the contrast to get brighter highlights, and maybe shifted the hue a bit to get the highlights whiter.