Nice shot! I think the head being in focus would have made it stronger that way the colors just melt together as you move towards the back of the fish. It does have that buttery warm color to it that is a nice contrast to it's dark surroundings. One thing I may have done would be to have the angle at which you've positioned the fish within the frame be a bit more interesting (maybe a tighter crop with a more diagonal positioning?). Anyways, very cool shot, keep it up!