Originally Posted by Budget aquarist
tripod is a must unless you have like, halides. - Dont use your flash, it stresses your fish and the pictures look ugly. I dont know about you other aquarium photographers, but i always have trouble with the auto focus and aquariums, i only use the manual with mine. and yes you kinda got to play with the shutter speed and the aperture settings for a while, it can get very frustrating sometimes. I know what it feels like to want to throw your new and very expensive camera on the ground.
I'll disagree with you here.
A tripod is only needed if you're shooting with a small aperture ie. f/11 with limited lighting. Tanks with lots of flow and fast moving fish, you'll see nothing but blur doing it this way, even with a tripod
Flash is your best friend actually when it comes to aquarium photography. The secret is what mistergreen already mentioned ---> using a remotely triggered flash! If you're shooting with the onboard flash unit or a mounted flash, the pics will look "ugly" like you stated. It won't look natural due to the angle of the shadows and possible reflection off the glass. The remote flash must be fired from above the tank to achieve the natural look.
As for autofocus, my lenses stays on AF 99% of the time. I have no trouble with AFing, as long as the aquarium glass is clean and the lights are on. Try shooting perpendicular with the glass pane instead of angled shots. This will yield the best image quality without distortion.
BSMITH - x2 on what mistergreen said. Just keep in mind when you're shooting with flash, it's best to have some sort of diffuser attached to it, otherwise the lighting becomes too direct oftentimes. I use a tripod to mount my flash on for simple adjustments over my tank. It also helps avoid dropping the flash into my open top tank.
If a macro lens is what you're next upgrade will be on, I suggest you get a fast lens - f/2.8!! You can thank me later for the advice.