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How Many Goldfish In A 10 Gallon Tank (For optimum health)

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Goldfish are known to be kept in fishbowls, often by themselves, but is this cruel? How much room do goldfish need? Is a 10 gallon tank big enough for goldfish? Should goldfish live alone? Many questions arise concerning the ideal tank size for a goldfish, so let’s dive in and find out how many goldfish in a 10 gallon tank?

You should only keep 1 goldfish in a 10 gallon tank, or you can keep 3 to 4 baby goldfish in a 10 gallon tank if you plan to move them to a larger tank as they grow bigger. A 10 gallon tank is the absolute minimum for a single goldfish. A bigger tank provides more room to swim and enough room for tankmates to keep your goldfish company.

How Many Goldfish In A 10 Gallon Tank

If you have already purchased a 10 gallon tank or only have enough room for a 10 gallon goldfish tank, this short article will answer the most common question, “Is a 10 gallon tank good for a goldfish?”

Can A Goldfish Live In A 10 Gallon Tank

A goldfish can live in a 10 gallon tank, but it is not recommended. A 10 gallon goldfish tank is definitely too small for a fully grown goldfish, and it may stunt the growth of young goldfish. A goldfish needs a minimum 20 gallon tank to be healthy and happy.

If you have a 10 gallon goldfish tank, you will need to be extra careful about the water quality, and you will need to carry out frequent water changes. It is also good to get a small goldfish species suitable for a small tank.

If you are wondering how long goldfish live, they have a long lifespan, so you would want them to be comfortable without having to keep upgrading their tank.

Best Size Tank For Goldfish

The best size tank for goldfish will depend on how many and the type of goldfish you intend to keep. There are over 300 species of goldfish, and they come in all shapes and sizes.

Some goldfish only grow to be a few inches long, while others can grow much bigger. The rule of thumb is that each average-sized goldfish needs at least 10 gallons of water.

Best Size Tank For Goldfish
The best size tank for goldfish will be at least 20 gallons, providing plenty of room for 1 or 2 adults.

Common Goldfish Tank Size

The recommended common goldfish tank size is at least 20 gallons per fish. Unlike some fancy varieties, the common goldfish is a slim-bodied goldfish that will take up less tank space in bulk but will grow longer than most fancy goldfish.

Common goldfish are also quite hardy, making them suitable for outdoor ponds, which have much more space than most indoor aquariums can provide.

What Size Tank Do I Need For 2 Goldfish

The recommended tank size for 2 goldfish is at least 30 gallons. Although I mentioned above that each goldfish would need approximately 10 gallons, I recommend that you begin with a 20 gallon tank for 1 goldfish. 20 gallons will allow room for heaters, filters, ornaments, and plants while allowing extra swimming room.

How Many Gallons Do You Need For 3 Goldfish

The recommended tank size for 3 goldfish is 40 gallons or bigger. For each goldfish after 2, you will need to increase the tank size by 10 gallons. So for 3 goldfish, you will need a 40 gallon tank and so on.

For larger fish, tank sizes should be bigger, which you can check by using the “goldfish tank size calculator” further down this article.

Should You Keep Goldfish In A Bowl

I wouldn’t recommend that you keep your goldfish in a bowl. Most bowls are too small and do not provide enough water for goldfish to move freely, grow, or thrive.

Goldfish are strong swimmers and require plenty of exercise, which they will not get in a small bowl, so they may become stressed and susceptible to increased bouts of illness.

Small tanks will often stunt goldfish growth as the lack of exercise and stress will cause a growth-inhibiting hormone to be released. It may seem like a good solution when using a small tank, but it will likely reduce the lifespan of your goldfish significantly as they tend not to live as long in such a small space.

Goldfish bowls do not usually have filters, which means the water quality will decline quickly, becoming dirty and harmful to goldfish as toxins begin to build up.

Small bodies of water are notoriously tricky to keep clean, and water parameters can change very quickly compared to larger tanks.

Minimum Tank Size For Goldfish

You can keep goldfish in any size tank, and they often are kept in tiny tanks and bowls; however, the absolute minimum tank size that I would recommend for an average-sized goldfish is 10 gallons.

10 Gallon tanks are ideal for very small fish or some goldfish babies. 10 gallon aquariums are great for breeders to use as a nursery tank where newly born goldfish can live safely until they have grown big enough to be moved into the main tank.

Although I have recommended 10 gallons as the absolute minimum tank size, this doesn’t consider any other fish. Goldfish are very social, preferring the company of other goldfish and other fish species.

A 10 gallon fish tank would be too small for the average goldfish to live comfortably, especially as most goldfish produce a lot of waste. Water conditions would decline rapidly with 2 goldfish in a 10 gallon tank.

Smaller fish tanks require regular cleaning and regular checks of the water parameters, especially if you want to keep healthy fish. Make sure you pay special attention to your fish tank pH, water hardness, and ammonia levels.

How Big Is A 10 Gallon Fish Tank

We’ve talked about how many goldfish to put in a 10 gallon tank, but how big is a 10 gallon tank?

10 gallons sounds a lot, but how does it measure up when looking at the dimensions of the physical tank? An average shape 10 gallon fish tank measures approximately 20 inches (50cm) Length x 10 inches (25.5cm) Width x 12 inches (30.5cm) Height.

You can see by the above measurements that a 10 gallon tank isn’t very big at all, and if you consider that goldfish can grow to around 12 inches long (or bigger), a 20-inch tank will heavily stunt the growth of your goldfish.

If your goldfish continues to grow to its full potential size, it won’t have much room to swim, which would be very unhealthy and stressful, and you should consider getting a larger aquarium.

I found the video below on YouTube that discusses some common misconceptions about goldfish tank sizes.

This interesting video discusses some common misconceptions about goldfish tank size.

What Goldfish Can Live In A 10 Gallon Tank

If you want to use a 10 gallon aquarium, some varieties of “Fancy Goldfish” will only grow to a maximum of 8 inches, making them more suitable. Some varieties that would be suitable are Bubble Eye Goldfish, Celestial Eye Goldfish, Pearlscale Goldfish, Pompon Goldfish, and Butterfly Tail Goldfish

Fancy goldfish have been selectively bred to create unusual features and colors, and this is also true of their size. Although the goldfish mentioned above are typically smaller, a 10 gallon tank is still a little small for an adult, and especially an adult that would benefit from some company.

Goldfish Tank Size Calculator

There are several calculations that you can use to calculate the amount of fish suitable for a particular size fish tank. Below is a list of the most common goldfish tank size calculations.

How Many Goldfish Per Gallon

1 x gallon of water (minimum) per 1 inch of (fully grown) fish length.

This is a common calculation suitable for goldfish and used for most fish species.

When using this calculation, you will need to use the potential size of the adult fish, so a goldfish that is currently 3 inches long but can grow to 12 inches long would require a minimum tank size of 12 gallons.

After the calculation, I always add 10 gallons as these are the minimum values.

This calculation also doesn’t consider the possibility of tank ornaments, filters, heaters, and plants, so you should use your due diligence and add a few more gallons per item.

Tank Surface Area Calculation

Another helpful calculation to ensure adequate oxygen per fish is calculated using the surface area.

There should be 24 square inches of surface area per inch of fish.

A fish tank that measures 20 inches long x 10 inches wide = 200 square inches.

Divide 200 square inches by 24 = 8.3, so a tank of this size would support 1 fish that would grow to a maximum of 8.3 inches or 2 fish that would grow to a maximum of 4 inches.

This calculation is best used if you have a tank that lacks suitable aeration methods, like a substantial filter or air pump.

10 Gallons Per Goldfish Calculation

The most popular calculation I have already mentioned earlier in this article is the method of adding 10 gallons of tank space for each fish that you add.

This calculation is best used for average-sized goldfish that grow to around 8 inches in length. For more comfort and better health, I recommend starting with a tank size of 20 gallons and then adding 10 gallons per fish.

10 Gallon Goldfish Tank Setup

The best 10 gallon goldfish tank setup would ideally require as much swimming space inside the tank as possible, so a shallower tank will provide more length or width.

If you are wondering what water temperature is best for goldfish, most goldfish are suitable for coldwater environments, so providing you can maintain a consistent temperature in the tank, you can forego the use of a heater which will add space.

A shallower tank will have a larger surface area providing better aeration and oxygen flow, so a filter is not vital but will help with tank cleaning.

Some slow-growing plants will be beneficial to help with the nitrogen lifecycle, feeding the healthy bacteria which reduce ammonia and nitrites.

Best 10 Gallon Goldfish Tank

When looking for the best 10 gallon fish tank for your goldfish, there are a lot of choices, not all of them good, so below, I have listed a few that are suitable with links to both Amazon and Chewy. The tanks I have listed are close to 10 gallons, although not exact. They are good tanks that I have used and can recommend.

BiOrb 8 Gallon Tank

BiOrob Aquarium
BiOrb 8 Gallon

The BiOrb is not quite 10 gallons, but it provides excellent dimensions for easy swimming due to the bowl shape.

The BiOrb has a built-in Led light, filter, and low-voltage air pump, all neatly packed away, providing even more space for your goldfish to swim.

The BiOrb is the ultimate goldfish bowl and also comes in a 4 gallon size.

Fluval Edge 2 – 12 Gallon Aquarium

Fluval Edge Aquarium
Fluval Edge 2 – 12 Gallon Aquarium

Fluval is one of the top names in aquatic supplies, and they don’t disappoint with the Edge 2 glass aquarium with a built-in filter and an led light that mimics natural sunlight.

This tank is just slightly bigger than 10 gallons but won’t take up too much space as it has a squarer design instead of the classic rectangle.

Marina 20 Gal Beginner Aquarium Kit

Marina Beginner Aquarium Kit
Marina Led Aquarium Kit

Just in case, after reading this article, you have decided to opt for a bigger tank, the Marina 20 Gallon Aquarium Kit for beginners is one that I would definitely recommend.

The kit contains everything you will need to get set up quickly and easily.

The Marina Aquarium Kit has a slim clip-on filter with quick-change cartridges and a long-lasting, natural daylight effect led bulb built into the hood.

It also comes complete with food, water supplements, a net, and more.

This tank will give your goldfish ample room and will provide enough space for a tank mate or some smaller fish.

What Goldfish Can Live In A 10 Gallon Tank

Because there are so many goldfish breeds and varieties, it can be challenging to know which would best suit a small tank.

I certainly wouldn’t suggest keeping more than 1 adult goldfish in a 10 gallon tank, and as I have already mentioned, goldfish do prefer company.

If you do only want 1 goldfish in your 10 gallon tank, I have provided a shortlist of some smaller goldfish varieties that you can pick from below. Their smaller size will allow them to swim more freely in a smaller space. I would also recommend buying a fish that has not come from a community tank and is already used to living in a small tank.

Goldfish SpeciesPotential Size
Bubble Eye
Celestial Eye
4-6 Inches
Butterfly Tail
4-8 Inches
8-10 Inches
10-12 Inches
Approximate Adult Size Of Various Goldfish Species

The above table demonstrates average sizes for each variety of goldfish, so you should expect some goldfish to grow bigger and allow for this when housing them.

Wrap Up

Hopefully, this short article has answered all of your questions about how many goldfish in a 10 gallon tank is a suitable number.

There are many things to consider when making a decision on how many fish you can keep together in a particular size tank, such as whether they will need tank mates and how big each fish will grow when fully mature.

A 10 gallon tank is acceptable for smaller goldfish, and you can house 1 or 2 small adult goldfish in a tank of this size, but it would be kinder to consider increasing the size to around 20 gallons if you have the space.

Frequently Asked Questions

Fantail goldfish usually grow to about 6-8 inches long, so I recommend only having 1 fantail in a 10 gallon tank. A 20 gallon tank would be more suitable and leave room for a tankmate.

I would recommend only having 1 Fancy goldfish in a 10 gallon tank. There are many varieties of Fancy goldfish, with most of them growing to between 6-12 inches which would better suit a 20 gallon tank.

Comet goldfish can grow to 12 inches, so it would be unsuitable for a 10 gallon fish tank as it would probably stunt their growth and lead to stress and general health problems over time. A bigger tank of at least 20 gallons would be more suitable.

I recommend only keeping 2 juvenile goldfish in a 10 gallon tank. As your goldfish grow to adult size, they will need a larger tank (preferably 20+ gallons.)

Common goldfish are typically considered small in comparison to fancies. Common goldfish can grow to 12+ inches in the right environment with a good diet and require a large tank.

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