Description: Taken in the Bahamas during my Underwater Photography specialty course..
It is a nice shot, but I think it would have more impact if the flamingo tongue was more in the diagonal. Now, I see that you used the 20mm lens, how much did you crop the image? It looks a bit soft to me. A macro lens would be more appropriate for this kind of subject.
Until returning from the Bahamas the only lens/dome combination that I had was the 20mm. I've since corrected that problem with the purchase of two more domes and a 14mm Fisheye, 15mm WA, and a 50mm Macro.
I had to crop the image a lot, and while you're suggesting putting the tongue at more of a diagonal, the image is true to the situation. The flamingo tongue was pretty much vertical where I found it on the Willaurie Wreck.
I think impact is the biggest problem - there is none. Non divers and even active underwater divers just would have no clue as to what they are looking at. All pictures are at their best when they can tell a story to anyone. There is always exceptions to instructional lectures, artistic macro shots etc but the is most important advice to give on this. Others would be subject and environment separation, maybe saturate the colors a little better. A macro setup would have given a better rendering and more artistic feel. - Keep at it with your new setup!
I'd like to see more color contrast in the image. Obviously this is something you can't always completely control. People have mentioned the lack of impact. There are a lot of similar colors here and maybe some more contrast or punch on the subject would draw you in. Perhaps a different angle would result in more black or blue to pull out the flamingo tongue? Make it "pop".