In short, yes, you are able to transfer your goldfish to your pond, but there are several things you must consider when deciding whether to and how you transfer them.
Firstly, you can be reassured that, even if your goldfish have lived in a tank for all their lives, they will survive in a pond. They are naturally wild creatures and will be able to find food in the form of algae so should lead well-fed lives. Also, temperature-wise, again, they are fairly well adjusted naturally to the cold water of a pond, but care must be taken in winter if your pond is at risk of freezing over.
However, a word of caution. In a tank, your goldfish have no natural predators (unless you have housed them with fish that eat other fish, but I imagine if you had you'd have found that out by now). When placed in a pond outside, they can be eaten by any number of creatures including other fish, ducks, herons or other birds. Your fish may not naturally fear a predator so would be at risk of making a fish supper for a greedy heron. Therefore, you may need to invest in a net to put over your pond to deter the heron or duck. You may also need to remove any other potentially predatory fish.
To transport your fish, put your fish in a doubled plastic bag or bowl containing a sufficient amount of water from the tank. If it is a short journey, a bag will be fine. A long journey of over two hours and a pump will be needed to circulate oxygen. Leave the fish in the bag or bowl in the pond for an hour or two so it can acclimatize, then it should be fine.
Firstly, you can be reassured that, even if your goldfish have lived in a tank for all their lives, they will survive in a pond. They are naturally wild creatures and will be able to find food in the form of algae so should lead well-fed lives. Also, temperature-wise, again, they are fairly well adjusted naturally to the cold water of a pond, but care must be taken in winter if your pond is at risk of freezing over.
However, a word of caution. In a tank, your goldfish have no natural predators (unless you have housed them with fish that eat other fish, but I imagine if you had you'd have found that out by now). When placed in a pond outside, they can be eaten by any number of creatures including other fish, ducks, herons or other birds. Your fish may not naturally fear a predator so would be at risk of making a fish supper for a greedy heron. Therefore, you may need to invest in a net to put over your pond to deter the heron or duck. You may also need to remove any other potentially predatory fish.
To transport your fish, put your fish in a doubled plastic bag or bowl containing a sufficient amount of water from the tank. If it is a short journey, a bag will be fine. A long journey of over two hours and a pump will be needed to circulate oxygen. Leave the fish in the bag or bowl in the pond for an hour or two so it can acclimatize, then it should be fine.