Oh man...here we go...plants are not a quick fix. It will help stabilize the system long term, but you need fast results...once again you are saying that the cause of the problem is not having plants????? Oh come on. He all ready stated that he added supplements that caused the problem.
7.8 is bad, but not awful. However a swing from normal, up to 8.9, down to 7.2, and then back to 7.8 is a roller coaster of shock to fish. :scared: That is just too much for them to handle. At this point, personally I would not recommend relocating them, as the added stress of acclimating may just finish them off. Get your pH stablized, but do it slowly. Rapid changes are bad.
Your pH is not that far off at this point. Keep it climbing slowly. Yes, the fish may die, as the stress may all ready have been too much.
Do you have good surface agitation? That is all you should need to oxygenate the water.
And I do agree that water changes are a good idea.