also in the future ph doesnt affect of fish bad since most fish are tank raised and can adjsut it only matters if the fish is wild caught , and you dont have to use r/o water just treat the tank with salt and raise the tmperature to 84 or 85 F
sounds like the fish may be stressed out or shocked. I recently bought a 8 inch red line severum, and it had a 6 hour car ride. When I got him in quarantine, he was kind of out of it, and just more of floating around freely. after a couple days he started acting more normal.
I've had to switch tanks before which required me to put my severums in buckets. In the transition they're water temp dropped. When I was ready to put them in the new tank I thought I had killed them. But they snapped out of it in a short time.