There are several methods available for transferring fish from shipping bag to tank:
Dumping fish straight from bag into tank is probably the worst method.
Floating the bag in the water for 15 minutes then releasing the fish into the tank, water and all.
Netting the fish out of the shipping bag and putting it into the tank.
Dosing, where you use a dose of AmQuel and NovAqua (a capful per ten gallons or ten drops of each per gallon) added to the receiving tank and a small squirt of each is added to the shipping bag as soon as it is opened, the net method is used from that point.
The use of a quarantine tank is highly recommended, especially for established aquariums.