The first goldfish I can remember having was Sammy. He came from a fairground in the UK, and we had him for years.   Unfortunately, we kept him in a round bowl, which isn’t really a great life for a fish, but he was healthy and lived for a long time.

Healthy Goldfish

Healthy Goldfish.

It’s best to keep goldfish in a tank, or even better, an outside pond, if you can have one.   It’s surprising just how much water and surface area even one small goldfish requires, when you do some research about it.

One school of thought says that you need 30 square inches of surface area per goldfish, another says that you should have approximately 20 gallons of water per fish.    Of course, the surface area would depend on the size and shape of the tank, but it seems that more is better.    A search using “water surface area per goldfish” will bring up a variety of answers to the question.

Pond full of plants.

Pond full of plants.

This pond shown above may be a little too full of plants for goldfish, but they will eat what they want anyway.    The water lettuce all disappeared from my pond in a few days, as the fish seemed to really like them.   Usually, I crop the pond weed every few months, and use it as mulch on the garden.
If you’re going to keep goldfish as pets, it’s a good idea to get yourself a good basic book on keeping goldfish, there are many available, even some on-line. The more research you do before getting your fish, the better, as you’ll know more about keeping them in the best of health.