How Many Goldfish in a 5-gallon tank

How Many Goldfish in a 5-gallon tank

Key Takeaway

If you are planning to keep goldfish, it’s important to provide them with a suitable environment to thrive. While a 5-gallon tank may seem like a decent size, it is too small for goldfish.

Goldfish require a minimum of 20 gallons for a single fish and an additional 10 gallons for each additional fish. Remember, the well-being of your goldfish should always come first, so make sure to provide them with a spacious and comfortable living space.

Goldfish are charming and beautiful pets that can bring joy and tranquility to any home. If you are considering adding a goldfish to your household, one of the first things you need to consider is the size of the tank or aquarium. In this article, we will address the common question of how many goldfish can be kept in a 5-gallon tank.

Understanding the Needs of Goldfish

Before we dive into the specifics of tank size, let’s take a moment to understand the needs of goldfish. Goldfish are active, social creatures that can grow quite large over time. They have a high waste output and need plenty of oxygen to thrive. Goldfish also require adequate space to swim and explore their surroundings.

Why a 5-gallon Tank is Not Suitable for Goldfish

While a 5-gallon tank may seem like a decent starting point, it is important to note that goldfish have specific requirements when it comes to tank size. A 5-gallon tank is simply too small to accommodate the needs of even a single goldfish.

Goldfish produce a significant amount of waste, which can quickly accumulate in a small tank and lead to poor water quality. Inadequate water quality can make your goldfish stressed, prone to illness, and can even shorten their lifespan. Additionally, goldfish need ample space to swim and exercise to maintain good physical health.

Ideal Tank Size for Goldfish

To ensure the well-being of your goldfish, it is recommended to provide them with a minimum of 20 gallons of water for a single fish. For each additional fish, you should increase the tank size by 10 gallons. Therefore, if you plan to keep multiple goldfish, a 5-gallon tank would be insufficient.

To give you a better idea of the suitable tank sizes for goldfish, let’s take a look at the table below:

Number of GoldfishMinimum Tank Size (Gallons)

As you can see, the tank size increases as the number of goldfish increases, ensuring that each fish has enough space to swim comfortably and that the water quality remains stable.

Ensuring a Healthy Environment for Your Goldfish

In addition to providing the appropriate tank size, there are a few other factors to consider when creating a healthy environment for your goldfish:

  1. Filtration: A good filtration system is essential for maintaining clean and clear water. A filter helps to remove waste, excess food, and other pollutants, ensuring a healthy and balanced environment for your goldfish.

  2. Aeration: Goldfish require well-oxygenated water to thrive. Make sure to invest in an air pump or provide some form of aeration to ensure an adequate oxygen supply.

  3. Water Quality: Regular water testing and maintenance are crucial in keeping your goldfish healthy. Perform partial water changes regularly and monitor the water parameters (pH, ammonia, nitrite, nitrate) to ensure they remain within the appropriate range for goldfish.

  4. Tank Décor: Goldfish love to explore their surroundings, so providing them with plenty of hiding spots and decorations, such as plants and rocks, will not only make their environment engaging but also reduce stress.


While a 5-gallon tank may seem like a practical option for keeping goldfish, it simply does not meet their needs. Goldfish require spacious tanks to thrive and should be provided with a minimum of 20 gallons for a single fish, with an additional 10 gallons for each additional fish.

By providing the appropriate tank size and maintaining a healthy environment, you can ensure that your goldfish live happily and enjoy a long life. Remember, it’s important to prioritize the well-being of your fish over convenience or aesthetics. Happy fish keeping!

– Goldfish Society of America
– The Goldfish Tank