Yes, this is a good idea.

If you use the rubber hood trick, it also makes it possible to use flash.... However, flash may not be allowed (check with the aquarium).

You also might find a quality circular polarizing filter helpful, controlling reflections off the glass (when you can't use the rubber hood/pressed against glass trick). I would recommend a "High Transmissive" (HT) C-Pol, such as the B+W F-Pro and XS-Pro series. HT C-Pol aren't as dark as typical polarizing filters. They block less light, which may be very useful if you need to use one in a dimly lit situation. A "standard" C-Pol blocks approx. 1.5 to 2.25 stops of light, depending upon the filter's setting. In comparison, the HT C-Pol block approx. 1 to 1.5 stops. That may not seem like a whole lot, but in low light situations it might be the difference between being able to "get the shot" or not.

Depending upon what lighting is used, you also might need to set a custom white balance. Be sure to know how to do that and to have a WB target available.

Shoot RAW (or RAW + JPEG). RAW files will need post-processing, but allow much more flexibility than JPEGs to adjust exposure, change white balance, control noise reduction and more.