Don't be lazy like me, I just didn't have a car to go get it
Go to J&L or heck, Revy and buy the stuff that gives a thumbs up for aquariums.
Personally, I phoned GE and they stated that it won't leach any chemicals (this was for the Silicone I) but that it's not designed to support building for an aquarium... however I've known people who've had tanks running for years with no problems, using Silicone I
If you have a car and a way to get there, just do Revy, or call GE on Monday and confirm.