Goldfish Aquarium – What size tank does a goldfish need?

The goldfish is extremely popular and suitable for indoor and outdoor use. If you want to keep a goldfish indoors, you need a large aquarium. But what should a goldfish aquarium be like?

An aquarium for an ordinary goldfish needs a minimum volume of 120 liters, and an additional 50 liters for each subsequent goldfish. For smaller types of goldfish, an aquarium of at least 100 liters and 40 liters for each additional goldfish is sufficient. The length of the goldfish at maturity determines the size of the aquarium.

That’s a big aquarium for 1 goldfish! Especially if you compare it with the well-known fishbowl where you sometimes see a goldfish.

Choosing the right size for a goldfish aquarium

Goldfish can grow very large and are very active swimmers. So you also need a long aquarium. I recommend a minimum length of 120 centimeters so that they can fully enjoy themselves.

In addition, goldfish also produce a lot of waste, especially ammonia, which quickly deteriorates the quality of the water. By taking a large aquarium, the concentration will increase less quickly, so that the bacteria in your filter have enough time to process them.

A goldfish also benefits a lot from water with a good oxygen content. Making the water oxygen-rich can be done with an air stone, but I prefer a natural solution such as plants or a large water surface. In particular, a large water surface ensures good gas exchange in the water.

They also like to live in the company of other goldfish and taking the above factors into account, this will mean that you will soon need a large aquarium.

Not every goldfish is the same

There are many different types of goldfish and they don’t all grow the same size. The volume of your tank should be calculated based on the final size the goldfish will be at maturity. Look here for an overview of the most popular goldfish and veiltails for an aquarium.

Some goldfish can grow up to 30 centimeters in length, while smaller species do not grow larger than 15 to 20 centimeters. Obviously, smaller species can live in a smaller aquarium.

Be well informed in advance by the aquarium specialist how big the goldfish can eventually become. You can use the table below as a reference for determining the minimum content and the extra required content per fish.

Adult height Contents Extra content per fish
up to 20 cm 100 liters 40 liters
20+ cm 120 liters 50 liters

Minimum aquarium volume in adult goldfish

Reference aquarium content for goldfish

In the table below you can quickly read how large your aquarium should be for a number of goldfish. This table only goes up to 4 goldfish, but you can safely put more together if your tank is big enough.

Number of Content (up to 20cm) Content (20cm+)
1 Goldfish > 100 liters > 120 litres
2 Goldfish > 140 litres > 170 litres
3 Goldfish > 180 liters > 220 litres
4 Goldfish > 240 liters > 270 liters
Minimum volume for aquarium with multiple goldfish

A large aquarium for goldfish is important

A goldfish needs space

If you see a goldfish swimming around in an aquarium store, they are only a few inches long. You would think that they will not grow much more, but nothing could be further from the truth! A standard goldfish can grow to a length of 30 to 40 centimeters if given the space to do so.

It may seem strange at first if you have two small goldfish in a large aquarium, but you will see that after 2 years they really need that space. That little goldfish that you have taken good care of has become a big boy.

A goldfish is also a very active swimmer. Besides the fact that you need a large aquarium, it is also important that it has a minimum length of about 120 centimeters. This allows the goldfish to move through the water at a rapid pace without having to turn around all the time. They really like that!

Goldfish swim back and forth, and not from top to bottom. A very small, high aquarium is therefore not optimal for the goldfish.

Oxygen is important for a goldfish

Sufficient oxygen in the water is very important for a goldfish. When there is a shortage of oxygen, the goldfish will try to gasp for air at the surface. Do you recognize this? Then you need more oxygen in your aquarium. You can increase the oxygen level in a number of ways.

The easiest way also has to do with the shape of your aquarium. The larger the water surface, the better the gas exchange between air and water. At the surface, the oxygen can be absorbed by the water, and at the same time the CO2 can also escape.

A second way is to place enough plants in your aquarium. These will also release oxygen to the water. The goldfish also enjoy playing with the plants or swimming through them. So a win-win situation!

You can also get more oxygen in the water by using an air stone. Such an air stone increases the oxygen content by blowing very small air bubbles into the water.

Goldfish are strong polluters

I can’t talk about it. Goldfish are very big polluters. They produce a significant amount of bio-waste to put it nicely. All the goldfish excrement has to go somewhere, and you guessed it: it ends up in the water.

In a large aquarium, the concentration of the waste will accumulate less quickly and can be removed by the filter within a reasonable time. After all, you have more water in which it can be absorbed.

If you have a too small (or smaller) aquarium, the natural balance of the water will be disturbed and you may have to deal with ammonia peaks in the water. The largest waste product of a goldfish is ammonia that ends up in the water via the gills and feces. This can lead to ammonia poisoning. A small aquarium does not have to be a disaster, but you will have to change the water regularly to keep the water in balance.

A goldfish does not like to be alone

If you read the title of this article you will see that it is about gold fishing , so plural. Goldfish prefer the company of 1 or more goldfish. Only one goldfish in an aquarium is pathetic, so make sure you have at least two. In addition, goldfish can easily live to be 10 to 20 years old and you really don’t want to let them live that long.

You will not see a goldfish swimming in schools, but they do enjoy socializing with another goldfish from time to time. At a water change they may feel anxious and then you will see that they will seek each other out to offer each other comfort.

More goldfish in your aquarium automatically means a larger aquarium. The minimum volume for 1 goldfish is really 100 liters, and for each extra goldfish you can add another 40 to 50 liters . So for 3 goldfish you quickly need an aquarium of 180 to 220 liters.

Certainly when all your goldfish are fully grown, you will see that that large aquarium is really not an unnecessary luxury.

Goldfish like decoration in your aquarium

Goldfish are very active in the water and enjoy nibbling on your plants, hiding or swimming around your decoration. So make sure that your goldfish don’t get bored and put a lot in it, but make sure that they can still swim freely.

Also provide enough hiding places so that they can retreat for a while or have a safe place to rest. Bridges in particular are doing very well.

The decoration in the aquarium does of course take up extra space: another reason that you need a large aquarium for goldfish.

Frequently Asked Questions

Can goldfish live in a fishbowl?
A goldfish needs at least 100 liters of water and is therefore not suitable for living in a fishbowl. A fishbowl is too small so the goldfish will grow poorly. A goldfish is also a strong polluter, which means that the water in a fishbowl deteriorates quickly and has to be changed often.

How big does a goldfish get in a pond?
Depending on the type of goldfish, it can grow to a length of 30 to 40 centimeters in a pond. A pond offers enough space for a goldfish to grow undisturbed. Not every goldfish is suitable for a pond because of the variable water temperature in winter and in summer.

How big should an aquarium be for 2 goldfish?
An aquarium for 2 goldfish should be at least 140 to 170 liters. The length that the goldfish grow to maturity is the determining factor in choosing the right aquarium. Goldfish can grow to more than 30 centimeters, which makes a large aquarium necessary.

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