The expression is really sad. The image is not defocused - it's just the fish moving (I think). Too bad that I did not see the author's comment at the voting time. If I knew the reason for 'sadness' I would gave this image higher score.
On the composition I would expect to see the fish eye in the middle of the frame and, probably, some side-lighting to get reflections from the scales, but that's difficult in the restaurant...