You can get those glass glue/silicon, to fix this, is this at the bottom of the tank? if yes, then probably you can't do both side, maybe only on the inside of the tank only.

but for me, i wouldn't risk it, i would probably get a new tank instead, new tank is not as expensive anyway. risk free and no headache.

your headache will come if you have leakage, you will need to rescape, rehome them, etc etc. so much to do.