Which Gorilla glue you talking about ... polyurethane or PVA?
I believe that both would be non-toxic when cured, but I am not sure of submerged use. The PVA (white/cream color) is only water resistant ... I use it for my outdoor project, but it will fall apart if continuously submerged. The polyurethane (brown bottle) is more water resistant, but I still won't trust it in fully submerged applications (it is rated HPVA type 2, not for continuous submersion.) Epoxy or silicone is better choice IMO
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.