How Much Tank Space Do Goldfish Need?
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How Much Tank Space Do Goldfish Need?

How big do goldfish grow? How long can a goldfish life? How much space do goldfish need? Is it true that a goldfish will only grow to the size of the aquarium? Do goldfish have short memories? How to care for a goldfish. Learn the facts about keeping a goldfish in a goldfish bowl or small tank.

Believe it or not goldfish may be one of the most abused pets. Often kept in tanks, bowls, and aquariums that are too small for them, many are stunted in size as a result. Perhaps it is because goldfish are cheap and easy to come by, that people fail to consider their needs to be important.

Goldfish were once thought to be stupid, with only a 10 second memory. This has been disproved as goldfish have been taught to swim a maze, and push balls through hoops. In fact their memory has been shown to be around three or four months. Yet many are kept in tiny bowls with nothing more than a plastic plant.

Goldfish have a lifespan over 12 years (one common goldfish lived to be over 40 years) and some varieties can grow to 16 inches (40cm) yet in many homes they live only a few short years and are often very small for their age. Why is this?

At one time people were told that it was okay to keep their pet goldfish in a small tank, they were told it would adapt to the small bowl and only grow to a smaller size. Indeed while this is true, it is not because of some great fish miracle, it is because in small bowls the water becomes extremely dirty, even within a few hours, poisoning the fish, and stunting its growth.

In many cases their growth is further stunted since many of the goldfish kept in bowls do not have aerators, the lack of oxygen in the water is also a contributing factor to stunting growth in these fish.

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A general rule of thumb for keeping any kind of fish is that the tank should be at least 1 gallon of water per 1 inch of fish. As such a fish that is 4 inches (10 cm) long would require a 4 gallon tank. Two fish of similar size would require an 8 gallon tank. But wait, you must also consider the size the fish is expected to grow to. Comets, shubunkins, and common goldfish tend to grow larger than fancy goldfish, and may do better in ponds rather than in small aquariums or tanks.

If your goldfish are expected to grow to 10 inches, and you have two, you would want to keep them in a 20 gallon tank, not a traditional “goldfish bowl”. It should even be noted here that goldfish bowls have been banned in Rome due to being considered as cruel.

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Comments (4)

Interesting facts and information. People tend to keep gold fishes in small size tanks but after my own experience of having an acquarium for few months I realized that it is really difficult to keep them healthy and safe in small acquariums.

Great Article. and I love that you mentioned it is cruel to not consider proper care of the goldfish. And they make great pets. My goldfish, Beau, is a fancy gold fish, he is about 2 inches long and he is about 10 years old. He is gorgeous and very interactive. He recognizes when I come into the room and swims to the front of the tank and then when I put my finger inside the water he swims up and around and around my finger touching me. He is great!! I keep him in a 10 galon tank with aereators. I change is water every week to ten days as goldfish water becomes toxic with ammonia levels very quickly. I can always tell if I have been a bit delinquent because he seems less interested and always perks up after a water change. I am happy to hear about the lenth of their memories. I did not know that. I assumed it was more than a a few minutes. Because he always knows me and sees me daily. The number one tip about goldfish is to not overfeed. They are great pets. And could teach a child great responsibility. thanks Brenda. 

Superb work! I have a 25 gallons aquarium where I put my golden arowana and thinking of getting a much bigger tank cause she's getting larger, thanks Brenda.

good article, I don't have fish though I never was able to keep them.