What's the secret to good aquarium photography?

More lighting in the tank. NO FLASH.

ALWAYS, use a tripod.

I’m with @ChazMaz.
I think a fisheye lens would be ironic and awesome…even a wide-angle would create cool images. Otherwise, just a standard lens should work. Share with us when you make this happen!!!!

With more lighting in the tank, you should be able to shoot faster.
You’ll have to experiment with the different picture settings on your camera.

Is there anything I can do if I can’t control the lighting on the tank? I’m talking about places like the Monterey Bay Aquarium.

Polarizing filter to get rid of glare from other lights, a fast lens so you can shoot faster (50mm anyone? Those things are great.), and going on an empty day so your tripod doesn’t bother people.

Just one more tip to add. If the aquarium glass is flat (not those round tanks) point the lens slightly to the left or right. Aiming straight at the glass – you may get some glare & other unwanted effects.
I have some pictures I took at our aquarium. If I find them, I’ll come back & post them.

Found a couple pics. Both were taken with an old camera with no tripod. This is of a tank filled with sea life in constant motion. It was well lit, so that helped. This is of a jellyfish, that was surprisingly fast moving (& the tank was dark), so it showed up just a tad blurry. But, no glare on the glass, since I took the shot at an angle.

I see you tagged this question with NikonD80. If that is what you will be using, you shouldn’t have anything to worry about. You could probably use the automatic settings & the pictures will turn out fine. Trying to create a custom setting, for each tank you want to take a picture of, will only slow you down & the difference in quality may not be worth the missed opportunity because you were fiddling with camera settings. Best of luck. Be sure to come back & share the pictures. :)

What has always worked for me is putting the lens right up against the glass.And dont have it angled at all because that will stretch things out of proportion.
Rounded tanks are a bitch and a half to shoot. Havent found a good technique for getting around that yet.
Always use a tripod
NEVER EVER USE FLASH
Try and have the fastest shutter speed you possibly can since fish move a lot and whatnot
I like to set ISO around 200–400. I tend to get the best results in that range. Anything higher gets grainy.

And the number one thing Ive found to lead to successful pictures. TAKE A LOT. Seriously, when I shoot my aquarium I take up to 200 pics and only like 5 are good lol. Take a ton and keep the good ones. Hooray for digital photography lol

Here are some that I took

You have some great tips. One thing I also recommend is adjusting your white balance. Your D80 will have some preset settings and you should be able to tweak this further to get it right. Auto white balance will likely be at least a little off.

Shoot right up against the glass, not at an angle. Your lens should be perpendicular to the glass at all times.

Thanks for the good tips everyone.

@xxii I do shoot in RAW-only so I can always go back and clean up the images a bit afterwards; I will read up / try out the white balance settings.

Ohhh yea i totally forgot to mention the white balance thing. I usually need to have it set to high florescence on my camera. Fish tank lighting tends to use a lot of blues so you need to adjust for that or it will come out funky