Is it fish-safe that quickly? I don't need something to be completely water-tight or hold a lot of pressure....just bafflesI used an epoxy to put the plexiglass baffles in my sump. I think it was weld-on 40. I could check the bottle to be sure though. It is thick. Much thicket than the more common weldons. A bit tougher to get a hold of though. You could borrow some from me if you were around seattle (not sure where yelm is.)
It would probably be cured in 8 hours or so, still might want to wait 24 tho.... so not sure it helps.