I feel like I got the lighting 'quantity' about right, as I didn't want the colorful background overwhelming the eel...although I might've wanted a bit more light on his snout. I feel like I got the eel focus good too. But while I always read "you don't want the background too sharp to lose the subject", in this case I've got two shrimp and a banded shrimp in that background.
Do people think a shot like this needed MORE focal depth, or less, or are there other major changes you'd have made? This is a crop of about 60% of the actual shot area, admittedly, and I wavered on where exactly those boundaries were (didn't quite get a nice diagonal through the main subject and his attendants....)
I think it looks fine to me. The shot shows an eel at a cleaner station, ie in its environment. I think the fact you got two of the shrimp and the eel in focus is amazing. I usually get one or the other. The lighting is fine...although I agree it looks as if the eel is lit better just below its head.
I think the depth of field is fine if you wanted to show the interaction of the shrimp with the eel.
That said I think the angle of the shot could be altered to provide that separation you mention between the eel and the background. If it is a 60% crop as you mention then definately getting closer to the subject if conditions and environment allow may also help. A lower angle to the subject may help with the separation you are looking for. Maybe a shrimp in the lower third of the image with the eel in the upper third on a diagonal may help the image jump out more at the viewer. The image is definately clean and the lighting seems fine.
