Goldfish Tank Size: How Many Can You Keep in a Small Fish Tank

Lauren Kiekbusch
Goldfish Tank Size

What is the ideal goldfish tank size? This is a very popular question among the aquarists. It is mostly believed that goldfish require a large tank.

No doubt, you will need a big tank for goldfish fisheries but you can even use a considerably small tank as well. However, few aquarists want to farm the goldfish in fish bowls or nano tanks. But, this is not a wise option to go for at all. 

In fact, if you want to know the perfect tank size for your fisheries plans, there are some factors to keep in consideration. Firstly, it’ll depend on the species that you will keep.

In general, fancy goldfish can sustain in a 3-Feet lengthy tank including a volume of 20 gallons per fish. Again, the typical goldfish needs a minimum of a 4-Feet long tank with a volume of 30 gallons for one goldfish.

That is to say, when you add one fancy goldfish, then you have to expand additional 10 gallons for each added new goldfish. Whereas, you have to add 12 gallons more for each extra common goldfish.

Today, in this article we will let you know how to specify the extent of your goldfish tank. 

Perfect Tank Size For A Goldfish

Perfect Tank Size For A Goldfish

As said earlier, your tank’s size depends on what species you are keeping in the aquarium. In addition to this, you have to consider how many goldfishes you will keep.

If you don’t maintain the proper tank size, then your fish won’t be able to grow up to its full potential. Normally, a mature goldfish can get bigger up to 12 inches in length. Therefore, you can’t really rely on the small aquariums.

Accordingly, one should not keep goldfish in bowls. Rather, it is better to keep a tank having more than 20 gallons for each fish. Though, if you keep common goldfish, then you will have to increase the size and volume of the tank.

What’s more, a bigger space is better for the common goldfish. Because, if they become bigger in size they need enough space to live.

Calculation Of Tank Size

The normal recommendation is to keep:

  • 20-gallon volume for each fancy goldfish 
  • 30-gallon volume for each common goldfish

However, if you only keep this size, then your goldfish can’t swim fluently inside your tank. So, in order to farm a goldfish for all its life in your tank, you should maintain the six times space rule.

That means you have to increase the utmost capacity of your tank six times more than the generally recommended volume. Thus, your fish will enjoy enough swimming space throughout the tank. 

Many hobbyist fishkeepers calculate their tank size by multiplying the infant goldfish size. This is totally a wrong process of calculation.

Because an adult fancy goldfish may be up to one foot long in size. Usually, they are around 6-8 inches. Again, common goldfish can have 7-10 inches. But, they can be up to 12 inches if there is enough space in the tank or pond.

In general, a goldfish gets its highest length when it is around 15 to 20 years. So, you can begin your goldfish project in a little tank and transfer them into a bigger tank or pond after they get larger in size.

If you want to see them at their highest length, then you should plan to take them into a perfect pond.

How Many Goldfish Can You Have in a Small Tank?How Many Goldfish Can You Have in a Small Tank

It is never recommended to maintain goldfish in a bowl. While growing up in a bowl, goldfish can’t grow up as a whole but their organs proceed to outgrow their body. This may occur a lot of health problems for the goldfish like buoyancy problems.

Minimum a 10-gallon tank is able to keep one fancy goldfish. That means you can maintain one or two fancy goldfish in the 20-gallon tanks. Or if you want to keep one or two common goldfish, then take a 40-gallon aquarium.

Goldfish Maintenance

Keep the tank completely purified and conduct water changes on a regular basis. We’d recommend you keep the maintenance twice a week. Expand 10 gallons more for each extra fancy goldfish. At the same time, you have to add 15 to 20 gallons if there is a new common goldfish added.

Another important thing you should keep in mind, you have to think about space for decorations and tank mates. (This is because you may like to keep them in a community.)

Caution: There are many small tanks available in the market that are only eligible for a few weeks or months. So, you have to change such tanks if you want your goldfish to grow up for years. 

Let us see a ratio chart for knowing how many goldfish you can have as per the tank size:

Tank’s ExtentFish Number/Size  
1 gallon1 inch of fish
1 square foot of surface area1 inch of fish
10 gallonsPer fancy fish
20 gallonsPer fancy fish
20 gallons plus 10 gallonsFor each additional fancy fish
30 gallonsPer Slim-bodied fish (Size A) 
40 gallons Per Slim-bodied fish (Size B) 
50 gallons-55 gallonsPer Slim-bodied fish (Size C) 
PondFor bigger sized Slim-bodied fish 
Goldfish Tank Size

It’s your turn! 

Calculate how many goldfish you can have in your tank now!  Thus, you can specify the tank size for keeping goldfish. There are some aquarium kits that only have a small size for hatches or baby goldfish.

Yes, you can buy those initially, but after a time span, you should take your goldfish into bigger tanks. Otherwise, the growth of the fish will be hampered.   

Where To Get Goldfish Tank As Per My Requirement?

Goldfish Tank

There are plenty of goldfish tanks available on Amazon.    

Check Goldfish Aquariums from Amazon, And, to be specific about our choice,    

Tetra Aquarium 20 Gallon Fish Tank Kit (10 Gallons)  

Aqueon Fish NeoGlow Aquarium Starter (10 Gallons)  

Aquarium Kit Fish Tank with LED Lighting and Filtration Included  (20 Gallons)

Docooler Desktop small Aquarium Clock

Something Beyond Goldfish Tank Size: Water Quality 

Tank size is not the only reason for your headache. Another important thing to consider is, maintaining the water quality. So, always surround your tank with clean water. You should keep clean water because there may be both smaller and bigger fish in your aquarium.

Or may have both healthy and unhealthy fish in your tank. So, if you don’t care about the unhealthy baby goldfish, and if they are not well-cared for, then you can’t hope to see your goldfish as lively as you wish. 

Here are some of the recommended goldfish aquarium cleaners:

KloudAway Freshwater Aquarium Water Clarifier

FISH PROS Fine Mesh Fish Tank Net with Long Handle

Fluval Biological Cleaner Aquariums

If you ask us to recommend some of the very Best Goldfish Tanks With Filters, then we’d write down these names:

Aquarium Kit Fish Tank with LED Lighting and Filtration Included

YCTECH 1.4 Gallon Aquarium (For hatches)  

Let’s Wrap Up

Goldfish tank size calculation depends on some other factors also. Please remember the above things as you want to know the perfect tank size for your fisheries plan. In addition to maintaining size, you have to keep fresh and pure water in your goldfish tank as well. 

Overall, if all the theories are maintained, you can hope for your goldfish project with elegance.  

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