IMO..if your pH is very close to what the water is in the bag, I'd let him swim out and turn off your day lights so he can settle in without being bothered by other fish.
The water in the bag has to be toast after 2 days. The main thing that affects them is sudden pH fluctuation (that can kill them if it is too much).
As Kathy mentioned PH is critical with fish. The PH in a bag drops like a rock with depletion of O2 and increase of CO2. I had fish come in with the PH of 6,7 and took a half day to accliment them. Some species of fish are hardier than others with handling PH swings ,,,GL