If you want to acclimate your goldfish into a new tank, do it slowly so the goldfish don't get stressed.
- set up your goldfish tank or pond in advance.
Let the water cycle and establish beneficial bacteria that will help regulate the nitrogen cycle and help deal with the ammonia produced by a goldfish.
- Add a dechlorinator that will eliminate chlorine and chloramine.
If you fill your tank with tap water, it will have one or both of these in the water. Don't bother buying fancy dechlorinators, just buy one that eliminates both.
- Float the bag filled with air and the goldfish into your aquarium water.
Let the bag float for 30min until the water temperature inside the bag matches the water in the aquarium. Goldfish can die if there are rapid changes in water temperatures.
- Open the bag, let the water mix and slowly let the goldfish swim into its new home.
Depending on the size of your tank, don't add more than a few goldfish at a time or your tanks ammonia levels might spike and kill all the goldfish in your tank. A cycled tank will help keep this from happening.