DSLR Camera Settings at Aquarium

I plan on paying a visit to the Atlanta Aquarium this weekend and as are most aquariums, it's pretty dark. So how should I set my camera for the best pictures? I've taken pictures at city aquariums before and the pictures come out grainy. I know I need to bump up my shutter speed and disable the flash, but are there other settings I should consider? I'll be using a Canon 40D.

I know this should probably go under the Photography forum, but I wanted enough people to see this post so I could get the best advice and opinions. Thanks.
 
It just depends on the lighting of the subject. I shoot in manual mode most of the time, and with my D90 I can get away with some high ISO without the grain. If your camera at 1000 ISO still isn't grainy, go with that.

I can't remember if they allow tripods or not there, so you might call first. That would really help.
 
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