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Last update: April 6, 2022

Goldfish Tank Size Guide – What’s the Minimum Tank Size?

Goldfish are a popular aquarium fish. They’re versatile, hardy, and come in various fun colors.

But before getting a goldfish, it’s essential to know the minimum tank size required for your new pet.

This article provides a guide to the minimum tank size for goldfish based on the type of goldfish. In addition, tips on creating a fun and healthy goldfish habitat are also provided.

So, whether you’re new to keeping goldfish or just looking for advice on how to improve your current tank setup, keep reading for information on everything you need to know about goldfish tank size!

How Important is Tank Size for Goldfish?

tank size for goldfish

Goldfish come in many different shapes and sizes. The most common type of goldfish is the fancy goldfish, which includes popular breeds like the comet, oranda, and ryukin.

Fancy goldfish can grow about 12 inches long which means that they will need at least a 50-gallon tank. If you want to keep more than one fancy goldfish, you’ll need an even larger tank as they are territorial fish that need plenty of space to swim.

The other type of goldfish is the single-tailed variety, which includes common goldfish. These fish can grow much larger than fancy goldfish, sometimes reaching lengths of 18 inches!

As a result, they will need an even bigger tank, at least 75 gallons for a single fish and 150 gallons or more if you want to keep more than one.

Now that you know the minimum tank size for goldfish, it’s time to plan your new aquarium. Use this guide as a starting point, but do additional research to ensure that your fish have everything they need to thrive.

With a bit of planning and effort, you can create a beautiful and healthy environment for your new goldfish friends.

What’s the Minimum Tank Size?

A good rule of thumb is to choose a tank of at least 10 gallons for one goldfish and 20 gallons for two goldfish.

If you plan on keeping moor or fantail goldfish, you will need an even larger tank.

What Happens If The Tank Is Too Small?

What Happens If The Tank Is Too Small?

If the tank is too small, the goldfish will not have enough room to swim and explore. This can lead to boredom and health problems. Goldfish are very active fish and need a lot of space to stay healthy.

Goldfish are destined to outgrow smaller aquariums, but they can grow quite large if you put them in a tiny bowl. This is because of the growth-inhibiting hormone (GIH) that builds up when water changes are frequent or constant.

Goldfish are known to live to 10-15 years old, however, this can be shorter because of a poor aquarium environment. 

Under the right conditions, goldfish have grown quite large–up to 18 inches or 45 cm! This is much larger than most people believe, and it’s all due to the growth hormone in their system, which allows for such impressive sizes under good living circumstances.

However, the average size for most goldfish kept as pets fall somewhere between 4-6 inches or 10-15 cm. This is still quite a big difference from what most people expect, and it goes to show just how much potential these creatures have!

Of course, there are always exceptions to the rule, and there have been reports of goldfish growing up to 2 feet or 60 cm. However, these are sporadic cases, and it’s more likely that you’ll see a fish around 1 foot or 30 cm if you’re lucky.

Even still, most goldfish will max out at around 6-8 inches or 15-20 cm. This is still a perfect size, and it’s nothing to be ashamed of!

Now that we know how big goldfish can grow, let’s look at how much they weigh. Most goldfish will weigh between 2.5-3 ounces or 70-85 grams. However, there are always exceptions to the rule, and some fish have been known to reach weights of up to 6 ounces or 170 grams.

This is quite a big difference, but it’s important to remember that weight can vary depending on the type of goldfish and the conditions of their environment. For example, goldfish in ponds are typically larger and weigh more than those kept in aquariums.

The average weight for most goldfish is somewhere between 2.5-3 ounces or 70-85 grams, but some have been known to reach weights of up to 6 ounces or 170 grams.

What Should I Feed My Goldfish?

Goldfish are opportunistic eaters and will eat as much as possible whenever they have the chance.

In the wild, goldfish graze on algae and other aquatic plants. However, most goldfish in captivity are fed a diet of pellets or flakes.

While goldfish can survive on a diet of pellets or flakes, they will thrive on a varied diet that includes live, frozen, or freeze-dried foods.

What Does My Goldfish’s Tank Need?

average goldfish tank size

When choosing the right size tank for your goldfish, there are a few things to keep in mind. 

Filtration

As we mentioned earlier, goldfish produce a lot of waste, so you’ll need a filter to handle the load.

We recommend choosing a filter with a flow rate of at least ten times the volume of your tank. For example, if you have a 50-gallon tank, you’ll need a filter with a flow rate of 500 gallons per hour.

Swimming Space

Goldfish are active swimmers and need plenty of space to move around, so don’t skimp on tank size to save money!

A good rule of thumb is to choose a tank with at least 10 gallons of water for every goldfish. So, if you have two goldfish, you’ll need a 20-gallon tank.

Your goldfish will also need plenty of hiding places and places to swim around in their tank. Be sure to add plenty of rocks, plants, and other decorations to give your fish many places to explore.

Goldfish are also messy eaters and will often leave food behind, so choose a tank with plenty of surface area to allow for uneaten food to decompose. Or find tank mates for your goldfish that will help keep the tank clean and tidy!

Enrichment

tank enrichment

Goldfish are intelligent creatures and need stimulation to stay happy and healthy.

So be sure to add plenty of rocks, plants, and other decorations to give your fish many places to explore. You can also add toys such as mirrors or floating balls to help keep your goldfish entertained.

How Do I Keep My Goldfish Tank Clean?

Now that we’ve covered the basics of goldfish care, let’s talk about keeping your tank clean.

Goldfish produce a lot of waste, so it’s essential to perform regular water changes to remove excess ammonia and nitrates from the water. We recommend performing a 20-25% water change once per week.

In addition to water changes, you’ll also need to vacuum the gravel and clean the filter media regularly. Gravel should be swept at least once per month, and filter media should be replaced every few months.

To help keep your goldfish tank clean, perform regular water changes and vacuum the gravel at least once per month. You should also replace the filter media every few months or as needed.

How Long Do Goldfish Live?

Goldfish are a long-lived species and can live for 10-20 years with proper care. However, the average lifespan of a goldfish is only 4-5 years. Most goldfish are kept in poor conditions and do not receive the proper care they need to thrive.

To help your goldfish live a long and healthy life, provide them with a large tank, plenty of hiding places, and enrichment toys. You should also perform regular water changes and vacuum the gravel at least once per month.

Why Water Quality Is More Important Than Tank Size

Why Water Quality Is More Important Than Tank Size

Water quality is extremely important to a Goldfish. Imagine you had to live every day with poor air quality, it wouldn’t be very nice for your health and well-being, and the same is said for a goldfish.

Water quality is much more critical than tank size for goldfish care.

Goldfish are also sensitive to changes in water quality, so it’s essential to perform regular water changes to remove excess ammonia and nitrates from the water. 

FAQs

Can Goldfish Grow to the Size of Their Tank?

Goldfish can grow much larger than their tank size, so it’s essential to choose a tank that will accommodate your fish as they grow.

What Are the Best Tank Mates for Goldfish?

tankmates for goldfish

The best tank mates for goldfish are other goldfish. They are social creatures that do best in groups, so it’s best to avoid keeping them with fish of different species without proper research.

Check our article on the best tank mates for goldfish here.

What Type of Food Should I Feed My Goldfish?

Goldfish are omnivorous, so they need a diet that includes plant and animal matter.

A good quality goldfish food pellet or flake food should provide most of your fish’s nutrition, but you can also supplement their diet with live or frozen foods like brine shrimp, daphnia, or bloodworms.

How Often Should I Feed My Goldfish?

How often to feed goldfish

Goldfish should be fed once or twice a day, and only as much as they can eat in two minutes. Overfeeding can lead to health problems like obesity and swim bladder disease, so it’s essential to avoid overfeeding your fish.

What is the Optimal Water Temperature for Goldfish?

The optimal water temperature for goldfish is between 70 and 75 degrees Fahrenheit.

What Are the Best Plants for Goldfish Tanks?

Some good plants for goldfish tanks include Anacharis, Hornwort, Java Fern, and Water Lettuce. These plants will help create a natural environment for your fish and provide them with hiding places and shelter from the light.

How Often Should I Change the Water in My Goldfish Tank?

You should change the water in your goldfish tank every two weeks, or more often if it becomes dirty. When changing the water, be sure to use a water conditioner to remove chlorine and other harmful chemicals from the tap water.

Can Goldfish Live In A Bowl?

fishbowl

Goldfish should not be kept in a bowl. Bowls are too small and do not provide enough filtration or aeration for goldfish.

In addition, goldfish produce a lot of waste, so they need a filter to keep the water clean and oxygenated.

Do Goldfish Need an Air Pump?

An air pump is not necessary for goldfish, but it can help to keep the water well oxygenated. If you choose to use an air pump, be sure to get one specifically designed for aquariums.

What Are the Best Filters for Goldfish Tanks?

The best filters for goldfish tanks are canister filters. Canister filters provide excellent filtration and aeration for goldfish tanks.

Do Goldfish Need a Heater?

Goldfish do not need a heater, but one can be helpful if you live in an area with cold winters. A good rule of thumb is to buy a heater that will raise the temperature of your tank by 10 degrees Fahrenheit.

How Much Light Does a Goldfish Tank Need?

How Much Light Does a Goldfish Tank Need?

Goldfish tanks need moderate lighting. However, too much light can cause algae growth, so it’s best to avoid using direct sunlight or very bright artificial light.

Do Goldfish Need Gravel?

Goldfish do not need gravel, but many people choose to use it in their goldfish tanks. Gravel can help keep the water clean and provide a place for beneficial bacteria to grow.

Final Word on Goldfish Tank Size

Goldfish are a popular pet, and for a good reason – they’re low maintenance and can be pretty charming.

However, it’s important to remember that they still require some care. One of the most important things you can do for your goldfish is to ensure you have excellent water quality.

This means testing the water regularly and making changes as needed. Tank size is also essential, so make sure you give your fish enough room to swim around and be happy. 

Have you ever kept goldfish as pets? 

What tips would you add?

Ian Sterling

I've been keeping fish for over 30 years and currently have 4 different aquariums – it's an addiction. I'm here to teach you everything there is to know about fishkeeping.

I also use this site as an excuse to spend lots of money on testing and reviewing different aquarium products! You can find my reviews here.

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