My pleasure!
My camera is a Canon EOS 1Ds Mark II DSLR, (16 megapixel), so the resolution is very high.
In terms of flash, the reason you do not see the shadows is a direct result of the technique itself, designed to eliminate shadows as hard shadows are in fact (in many professionals' opinion) what make this type of shooting look truly unnatural.
So here I used 2 Canon 580EX external flashes-- one mounted above the tank, the other handheld, down low and angled up toward the subject, and stopped down 1/3. In this way you capture the subject "in between" the two flashes and the shadows are effectively cancelled out.
I am also using a wireless trigger to fire the flashes. The Canon version is model ST-E2.
With the dual flash set up, you can shoot VERY fast (1/200 for my camera is not a problem), use very big f-stops (again f/22 here), and shoot very low ISO (100 in this instance, those these are all pretty typical settings when I do specimen shooting/macro work).
So indeed, a big part of the of the high clarity, very wide color gamut, and very low noise is owed to the high-end equipment I am using, but there is of course some knowledge of how to use it necessary. For sure very similar and even outright superior results can be achieved with a decent mid-range DSLR and the two flash set-up.
I also shoot 100% RAW. The RAW file-- unlike a jpeg-- is more like a "digital negative". It allows you to imbue the image with a truer sense of what you as a human being see in the aquarium-- not what a soulless digital camera sees. The sensor is in effect is only capturing the base light/color information. Editing with RAW file software allows you to add the data yourself that normally you would have left up to the camera to do for you. It's more complex than what I can lay out here in single post, but hopefully that gives some sense of what's going on here.
So, I only kindly ask that my work not be discriminated against simply because the approach is different. This is something I have studied and spent years working hard at. I have not added any color that was not there to begin with, and I actually use saturation with great caution, as when you push saturation too hard, and inherent symptom is graininess and blotchy or blown out areas of the color gamut. I don't believe in a lowest common denominator system when it comes to photography-- that obviously makes no sense.
Not to shamelessly plug another site, but it is so educational, I think it's OK-- but do check out this site dedicated to this type of shooting. It's
www.aquatic-photography.com and it's all about aquarium photography and how to do create better images of your fish. many of the regulars there are far better than me, for sure, and you can really learn a lot. Many of the images I see around the internet are typical of beginners-- they are just pointing their camera at the tank and accepting what they get back. There is a more precise way to do this, and the results are so enjoyable.
I'd love to help anyone get better at photographing their fish and aquarium. There countless Photoshop techniques to very simply make your images better-- not manipulate them into something they are not, but bring to life what is actually there.