What Size Tank for Goldfish?

A goldfish bowl is not a good home for your goldfish! Find out how to choose the right size tank for your goldfish.

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Introduce the article

As a beginner, you may be wondering what size tank for goldfish is best. The answer to this question is not as simple as you might think. The size of the tank depends on many factors, such as the type of goldfish, the number of fish, and your personal preferences.

In this guide, we will discuss all the factors you need to consider when choosing a tank for your goldfish. By the end of this article, you should have a good idea of what size tank for goldfish is best for you.

The three main sizes of goldfish tanks


A small goldfish tank is any tank that is under 20 gallons. This size of tank is not recommended for beginner goldfish keepers as they require more frequent water changes and are more susceptible to water quality problems. However, if you are experienced and have the time to care for a small tank, they can be a great option for housing goldfish.

Some common small goldfish tanks include:
-5 gallon tanks
-10 gallon tanks
-15 gallon tanks


The next size up from a small tank is a medium tank. These tanks are typically between 20 and 40 gallons in size. A medium tank is a good choice for keeping a small group of goldfish, or for keeping a single fish with room to swim. Medium tanks also offer more options for decoration and filtration than small tanks.


The large size is 120 gallons and up. These tanks are big enough to house multiple goldfish and provide them with plenty of space to swim around. You’ll need to have a filter and a heater for this size tank, as well as regular maintenance to keep the water clean.

Factors to consider when choosing a size

One of the most important factors in choosing a goldfish tank is the size. The size of the tank will determine how many fish you can have and the type of fish you can have. It is important to choose a size that is appropriate for the type of fish you have.

The number of goldfish

When choosing a size, you need to take into account the number of goldfish you have (or plan to have) and the size they will eventually grow to. A good rule of thumb is to allow 2 gallons (about 8 liters) of water per inch of fish. So, if you have two goldfish that will each grow to be 4 inches long, you will need a tank that holds at least 16 gallons (64 liters) of water.

The type of goldfish

There are different shapes and sizes of goldfish, and this is one of the main factors you need to consider when thinking about what size tank to get. Some goldfish grow to be over a foot long, while others only grow to be a few inches. It’s important to do your research so you know how big your goldfish will get and can plan accordingly.

Another factor to consider is how many goldfish you want. It’s generally recommended that you have one gallon of water for each goldfish. So, if you want two goldfish, you should get a two-gallon tank. If you want five goldfish, you should get a five-gallon tank, and so on. This rule of thumb will help ensure that your fish have enough room to swim and that the water stays clean.

The space you have available

One of the first things you need to consider when choosing a size for your goldfish tank is the space you have available. It’s important to have enough room for your fish to move around and be comfortable, but you also don’t want a tank that’s too big for the space you have. A good rule of thumb is to allow for at least 10 gallons of water per goldfish.


After reviewing the various factors involved in setting up a goldfish tank, a 20-gallon fish tank is the minimum size you should considering for housing goldfish. Larger is always better, but if you are limited on space or budget, 20 gallons is the smallest you should go.