Here's my replies....
(I use a Canon A70, Nikon F2, Minolta SRT100 and Nikon D100)
Do you use a tripod?
Always!
Do you use a special lens (i.e. macro) when taking your pictures?
On the fixed lens A70 I use closeup rings and polarizing lenses. The SLRs I have a lot of lenses/filters for.
Do you use a flash?
Not always but yes, depending on the photo you want. Many people say no to flashes but all it takes is placing the camera on an angle to avoid reflections. The biggest difference is the lighting, plants are better taken without flash, fish are easier with the flash so you don't have to use long exposure times. Entire tank shots are better with a low flash during a long exposure to eliminate shadows in the lower parts of the tank.
Here's some samples with the flash on:
http://www.gpodio.com/gallery/fish4.jpg
http://www.gpodio.com/gallery/fish5.jpg
If you use a flash is it on camera or off?
Both, usually on if the tank lights are providing all the light from above. If I need a full frontal shot of the tank then the flash is either turned off or placed at an angle away from the camera. The A70 and other cameras without a hotshoe or remote flash trigger require a little DIY to use a remote flash but it's worth it if it's the only camera you have.
Do you add supplemental lighting?
I do at times place a light strip on the floor a few feet from the tank, this reduces the shadows created from having light just on top. This is helpful if you have some overgrown plants that are too close to the front glass to get any light under them. It eliminates the need for a flash for full frontal shots.
Do you edit your images in an image editing software before posting them?
Very rarely, if it's a perfect shot but under/over exposed I do edit the histogram and contrast settings but most of the times I prefer not to touch the photos. Coming from a film background I like to make the photo perfect from the camera or during development.
Are you using auto focus or manual?
Both, closeup shots I usually use manual focus but my eyes are not very good so at times I have to rely on autofocus. Full tank shots I rely 100% on autofocus as the depth of field is sufficient to place everything in focus. Fish shots have to be manual focus as the fish keeps moving and the autofocus rarely picks it up correctly.
Are you using other special camera settings like manual exposure or manual aperture?
I only use manual settings besides the autofocus.
Do you use specific white balance settings?
Manual setting on the digital cameras using the white sample in the tank. For film, different films have different sensitivity ranges so this is the easiest way to correct white balance (Kodak for example is sensitive to blue, Fuji to red....). A more expensive method is to take the first shot of the white sample in the tank and instruct the processor to use that as the white balance during development.
Do you have any suggestions for the best settings on the specific camera that you are using?
As others said, time delay or remote shutter is best. The A70 is quite easy to use, doesn't take very good shots at anything over 200 ISO but longer exposures and lower ISO is better anyway. Oh yeah.... turn your filters off!! You want the plants to sit still during long exposures. If you have the opportunity to darken the room properly, early morning is the best time as this is when the water is at it's clearest and when plants are not pearling.
Are you using special metering modes?
No.
That's about all I can think of, the rest is all trial and error.
Giancarlo Podio