Wow, great suggestions.... wear black, carry a black velvet drop cloth and adjust around lens so as to reduce reflections.
My experience is at the Shedd Aquarium in Chicago, a million gallon tank (lots of water) and glass all around. Exposure was equivalent to ISO 2000 1/125 sec at f/2.8. These fish move and do not follow directions. I do not recommend a polarizing filter as the loss of light IMO outweighs any reflection changes. The black cloth will kill all reflections. The rubber lens hood is also a good idea or black gaffer's tape around the lens.
Lens is 24mm- 50mm on DX format. Longer lenses are not so useful as the water has a lot of haziness and some debris, and this will be exacerbated the longer the focal length. So, the bottom line with the D90 is maybe an f/2.0 or faster lens of somewhere between 24 and 50mm so an exposure of 1/125 sec at f 2.0 can be used at ISO 1000.
All this is what I experienced at the Shedd in Chicago with a D200 in 2007. And, I will tell you, I did not do well as I had only an f/2.8 lens and did not shoot at a fast enough shutter speed. Good luck!
Now, for the other exhibits...the 105 may be good...lighting is quite variable. And the black cloth will be useful there as well.