Wish this was clearer, the lack of focus (or at least sharpness that might be lost due to this being shot through glass?) really hurts this image. 4 from me.
The lighting conditions must have been pretty dark for this image, as it appears to be suffering from camera shake. You might want to crop this to eliminate the negative space on the right (empty water area). This would also help the image by moving the main subject off center (rule of thirds).
Nice shot. Very creative/unique. Suggestion that would improve this (IMHO): faster shutter speed so the fish wasn't blurry and not such a centered shot.
This could have been a beautiful image if the focus had been better. It appears that your background column is more in focus than the foreground, yet the brighter colors of the foreground make the eye want to see that part of it in focus.