How to Properly Transfer Fish to Your Pond:
When your fish arrive, open the bag to get some air to the fish and loosely tie the bag back up - only tight enough so the fish don't swim out of the bag. Don't allow any pond water to get in the bag yet. Put the bag of fish at the edge of your pond in the water where it's deep enough for the bag to be exposed to the pond water, but not too deep that the bag floats away. If the pond is in the sun, drape some newspaper or white towel over the bag and leave the fish there for 20 minutes so they get used to the temperature change first. After 20 minutes has gone by, open the bag and put about a cup of pond water in the bag. Close the bag and drape with the white towel and leave the bag of fish in the pond water. (This volume is assuming you have a bag that is about 1-2 gallons in size.) Wait for 10-15 minutes. Repeat this step again, adding another cup of pond water to the bag of fish. Do this step at least 3 times, waiting the 10-15 minutes between adding pond water to the bag. After you have nearly doubled the volume of water in the bag, slowly open the bag and let the fish swim out of the bag into the new pond. They should slowly swim out of the bag and discover their new pond and home. By acclimating the fish to their new pond this way, it will ensure a successful transfer and your fish should adapt well. This whole transfer process will take about 45 minutes - 1 hour. If at any time you see your fish in distress, especially gasping at the surface, immediately release them into the pond. They may sit there for a few minutes trying to adjust to the water, but they should be alright. Usually fish will be okay when transferred in a bag with their aquarium/pond water for about 1 hour, unless oxygen was added to the bag, where you'll probably have a bit more time (allow for driving time home, etc. when picking your fish up and immediately start the acclimating process). Naturally, this depends on the type of fish and it's size, but the rule of thumb is, that you must acclimate them to the new pond water gradually, as described above, and if found gasping at the surface, they are being deprived of oxygen. Unless you have an oxygen tank to give them more oxygen, the only way they'll survive is by putting them in the pond where there should already be plenty of oxygen.