I open up the fish bag and tuck it into the fish tank hood so that the bag is "floating" in the water. This helps make the water in the fish bag the same temperature as the fish tank. Next, every 15 mins or so I take a turkey baster of water out of the fish bag and throw it out (DON'T PUT IT IN THE TANK!), then put a turkey baster full of tank water into the bag. The goal is to slowly replace the fish bag water with tank water so that when you net out the new fish and add it to your tank, it won't be as much of a shock. This is especially important for large PH changes.