I took both pictures inside the Atlanta Aquarium. It was handheld without any bracing of any kind at the settings below, Jeff
Remember these were also cut way down in size so that I could post them.
1st picture
Nikon D7000
Sigma 17-50 F2.8 EX DC OS HSM lens
1/5 sec
Taken at F2.8
at 17mm
ISO 200
2nd picture with the yellow sea horses in it and all the color under water
Nikon D700
Sigma 17-50 F2.8 EX DC OS HSM lens
1/13 sec
Taken at F 2.8
17mm
ISO 640