Not lighting trick...just lighting. I use two Nikon SB-800 flash units and a Nikon SB-900 flash unit. Two on the top, one on the bottom shooting through a diffusion sheet of opaque plastic. On each side of the tank I place a reflector. That's part of the process.
With that amount of light I am able to shoot at a very low ISO (100) and use a very high aperture f32. This gives you a lot of latitude in capturing both detail and color. All of the images are shot in camera RAW (which collects 16 channels of information rather than the standard 8 in TIFF or JPEG). The images are processed in Nikon's Capture NX and converted to TIFF images. That is done in Photoshop.
The bottom line is that I have been a photographer for fourty years....learning the camera basics with film cameras. Believe me when I tell you that this might be the single best advantage that I have...camera basics. Today's digital cameras make it to easy to be comfortable with point and shoot. I try to challenge myself every time I pick up the camera to shoot photos...trying NOT to just grab another picture of a fish.
I worked as a military photographer for nine years photographing not only autopsies (where I honed my macro photo skills) but also for American Forces Radio and Television where I carried either a film or video camera all the time...three years in Europe and three in Asia...plenty of photo ops to practice. I also spent two years as the photo editor of a military newspaper in Fort Carson Colorado. I worked for NBC 21 years and have owned an advertising agency for eight....both of which requires me to think not only on a creative scale, but also with photo/video imagery.
It all boils down to practice, experience and a desire to improve every time I pick up a camera. And yes, I do have some nice equipment: Nikon D200, D300, D700 and D3...as well as a half dozen high end film cameras.
I take a couple hundred photos every week. But if someone wants to write off what I do to "lighting tricks"...have at it. I do what I do because I enjoy it. I'm not really interested in convincing anyone otherwise. And I do think that folks enjoy looking at my pictures.
Mo