well, if you have a more sensitive fish-- test the pH in the water. IF the fish has been in the bag a long time, the pH will be low ( 7-7.8) which is good because it makes the ammonia less toxic. IF you drip the fish the internal bag water will grow more and more toxic as the pH adjusts higher. So 'if' the fish is a known to be a sensitive species and 'if' the fish has been in the mail for 24-30 hours-- to be super safe it is best to lower your source water to the same low pH in a separate container and use that water for acclimation. If you think about it, most the damage a fish will experience is during acclimation as bag pH rises and ammonia becomes more and more toxic. With hardy species, it might be wise to adjust the pH lower to equal the bag and adjust temperature to exact and, IF your water is not peculiar in some other parameter-- simple move the fish from the bag to the adjusted pH water in the container and THEN begin acclimation to the actual pH of the Qtank water