Pretty much any silicone will do the job. I used liquid nails to hold the front panels on an enclosure with swinging doors but you're better off with something that won't set too hard. A little bit of flex at the joint will allow for expansion due to temperature rises/drops and for a bit of movement if and when you move the enclosure around so the glass doesn't crack.
Silicones don't usually adhere to wood with any real structural strength - they can usually be peeled off wood or painted surfaces fairly easily. Some of the specialist polyurethanes, such as in the Sikaflex range, will do a better job. Just check the cartridge for a list of compatible surfaces. However, silicone rubber may be adequate if strength isn't an issue.
Hay guys! Cheers for the advice! Well strength isn't really an issue but maybe it is? Just don't want my carpet lifting it off the tank but think silicone or sikaflex will do the trick. Just wanna bond the wood frame to the glass and have a lid on it.
Routing 2 grooves for the glass to sit in is a much better option.
Even a small piece of glass can have horrible results on human flesh if it's dropped.
Just be aware that aquarium makers use "Bostik V2" silicone to make tanks, not the "aquarium" safe selleys they sell at bunnings.
Spending an extra few dollars and saving your toes is a much better option IMHO, get it routed.
Rout the wood then use a bit of aquarium silicone (Bostic v2 acetic) and should be ok. Alterantively you could try using the hinges made for glass doors such as shower doors? Some of the dont even require drilling the glass.