I just wrote up a thing on how I get good pictures for someone, so I thought I would share what I use. This is just copied and pasted.
Well I use a standard Nikon D80, few years old, and standard lenses. I have a 24-85mm lens and a massive 70-300mm lens which is a bit harder to take pics with, requires a tripod. However I have found its not the lenses, rather the internal settings of the camera and lighting. I think the biggest thing is the lighting. You will need to turn white lights all the way up, and blue lights up as much as possible, and to get the best color, a flash of some sort. I'm using the built in flash right now and it works pretty well, but a purpose built external flash or two positioned correctly will give you stunning photos.
As for the internal settings, you want the ISO to be as low as possible while still allowing for the most amount of light and no movement blur. I like around 400-800. Any higher and you get grainy pictures. I always shoot on Manual, And tend to keep the Fstop pretty low, which Focuses the object, but leaves others even a slight distance away blurry. If I had a flash I think I could get around this and get more focus. I also Keep the shutter speed around 150-200, fast enough to stop all motion, but not too fast to start darkening the picture.
However the most stunning thing that I figured out, was changing the white balance settings. I have the standard "sunny" "cloudy" "shade", but I found a color temp setting. I set it to around 6,700K and that seems to really bring out all the colors without letting the blue lights mess up the picture. I have yet to try a yellow filter on mine but I do plan on trying it soon.
Anyways, that's how I get best results. I'm sure others will give better options too. And I also never photoshop any of my photos, so what you see is what I shot. Check out my facebook page for some photos that I took. The photos of the 10G tank are using the method described above.
https://www.facebook.com/Andrew-Porter-Photography-1395856257321224/timeline/