How Many Goldfish Can You Have Per Gallon of Water?

-- By Carol

Before you venture into the world of pet fish, one of the first questions that will come to your mind is to figure out the right fish tank size.

Depending on the kind of fish you’re planning on getting, tank sizes may vary. The most common kind of fish that you can opt for is goldfish because they’re easy to take care of and fun to watch.

So, how many goldfish can you have per gallon of water?

The general rule of thumb is that you need one gallon per 1 inch of goldfish. The last thing you want to do is have too many goldfishes crammed in a tiny space.

Ask any fish owner and they’ll tell you that tank size has always been very important.

It determines how freely your fish can swim around. It also plays a role in how happy and healthy they are.

Here are some rules to keep in mind when getting a tank for your goldfish.

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What Size Tank Should You Get?

Tanks usually come in sizes from 2.5 gallons to 210 gallons.

The larger your tank, the fewer the chances of fish waste building up, your fish getting sick or stressed, and pollution in the tank.

It also reduces the chances of the disease spreading from one fish to another.

Even if you follow the one-inch of fish per gallon rule, keep in mind that goldfish grow very rapidly and will need a bigger tank soon.

There are several other factors, apart from the size, which may help you find an appropriately sized tank for your fish.

What Size Tank Is Right for Goldfish?

Are you thinking of the long-term and want to invest in a tank that will keep your fish healthy and happy? Some fish owners go by the rule of 20 gallons of water per fish.

This means that in order to keep two goldfish healthy, content, and able to breathe and feed freely, you should have a 40-gallon tank.

This ratio is suitable for smaller goldfish, which grow to 6” on average. Alone, they can live in a 10-gallon tank, but to be happy they need at least 20 gallons.

And if you’re aiming for 3 or more goldfish (which is preferred), then 60 gallons is a safe size to opt for.

For 6-8 goldfish, a 120 to 160-gallon tank is the optimum size.

Smaller tanks need more maintenance, such as regular cleaning and water changes. This is because fish waste and pollution build up pretty fast in a smaller space.

When changing an aquarium’s water, your fish undergo a shock from the temperate change.

Regularly experiencing a disturbance in the water temperature can make your fish sick and stressed.

They need time to adjust to the heat and cold, so a larger tank keeps them healthier. This is because its water doesn’t get contaminated as quickly as a smaller tank.

Unlike some other species of fish, goldfish prefer being around other fish. They’ll get depressed and may even die if they’re left to live a lonely life by themselves. That’s why you need a tank that’s big enough for at least 2 or 3 goldfish at a time.

Tank Size Also Depends on the Kind of Goldfish You Have

Depending on whether you have fancy or slim-bodied goldfish, they’ll need differently sized tanks.

Fancy goldfish tend to grow to bigger sizes. They’re longer in length and larger in width as well. In fact, if you get a fancy goldfish, you should assume that it will grow double the size of a single-tailed goldfish.

Additionally, if you have goldfish with hoods, they need larger tanks.

Their hoods make it harder for them to breathe, so they need a tank with more surface area for water. They use this extra surface to oxygen more easily.

Goldfish with hoods typically include Lionheads, Ranchus, and Orandas.

How Old Are Your Goldfish?

Knowing how old your goldfish is at the time of purchase will save you the hassle of having to change your tank later.

For example, if your goldfish is one-month old, they still have several years of life ahead of them. And surprisingly, goldfish will grow for their entire lives if cared for properly.

By this standard, you should get a tank that will be big enough for fully-sized goldfish of 10-15 years.

You can predict their final size based on the type of goldfish and how old they currently are.

The Depth of the Aquarium Matters too

Fancy goldfish like to take their time as they swim across the tank.

They’re considered slow swimming fish and need a tank that has a larger surface area. The more the surface area, the easier it is for them to breathe and feed as well.

Apart from getting a larger tank, you might want to opt for a rectangular-shaped one. They’re long but aren’t as deep, which is exactly what these fish need.

Check the Surface Area

There are usually two kinds of tanks: deep tanks that don’t have as much longitudinal length or shallow tanks with more surface area.

Different kinds of goldfish prefer different combinations. However, most goldfish want tanks that are wider, not deeper.

This gives them ample space to move around, breathe, socialize, and feed. Ideally, for every 1 inch of fish, you should have 12 square inches of surface area.

Do Goldfish Prefer Larger Tanks?

If you have a big goldfish, they’ll prefer a larger tank.

Goldfish can usually grow up to pretty chunky sizes, so you might even have to upgrade your tank after a while. The bigger the tank, the easier it is for your fish to swim around.

If you’re starting off with a baby goldish, a small tank should be fine. However, keep in mind that it does have the capability of outgrowing its tank.

Opting for a bowl is a bad choice, as traditional as it may look. Goldfish need ample space to keep themselves entertained and happy.

Unlike most other fish, goldfish are bulkier in shape. You’ll notice that when a goldfish is in a tank that’s too small for its size, it’ll have trouble breathing.

It’s also likely to become sick from lack of regular food intake and will often be found floating near the bottom of the tank.

There’s a common myth that a goldfish only grows to fit the size of its tank. However, this only happens because they’re not fed or cared for properly.

If you regularly change the tank’s water and keep a close eye on your fish’s health, it can actually grow much larger.

The common goldfish has the capacity to grow up to 8 or more inches. They only remain small because they’re inhabited by space, which is essentially unhealthy.

If you want a healthy fish that lives longer, don’t limit its growth by the size of the tank.

How Many Sizes of Tanks Are There?

Tanks are labeled, according to the number of gallons they will hold. Ideally, you should not get a tank that holds less than 10 gallons because the average goldfish will outgrow it.

Any tank from 2.5 gallons to under 10 gallons is better for keeping a solitary fish, which isn’t preferred for goldfish.

If you’ve made up your mind about starting small and upgrading your tank as you go, start with a 10- gallon one.

A tank of 10-20 gallons is a safe size. However, this isn’t a viable size for more than one goldfish and should definitely not be a permanent home.

A 30-gallon tank is great for a couple of small goldfish. You can keep them there until they’ve outgrown it.

Again, this is not a sustainable option for 3 or more fish if you want your fish to be healthy.

What If You Don’t Have Space for a Large Tank?

The correct answer for dealing with limited space for an aquarium is simply to get fewer and smaller fish.

If you can’t fit a tank of more than 10 gallons in your house, you should only have one tiny goldfish. You could opt for a different breed of fish instead if one goldfish isn’t enough for you.

Another solution is to get a differently shaped tank. For example, if you can’t have one large aquarium sprawled along a wall, get an L-shaped one.

Rectangular aquariums give fish more space to breathe and swim, and they’re not too deep either.

Final Words

You may have heard that goldfish don’t have very long lifespans. However, as mentioned above, they can live for as many as 15 years.

The only reason people aren’t able to keep their fish alive for this long is that they don’t take adequate measures to keep fish healthy.

A healthy fish doesn’t just need food and clean water. It needs companions, a large space to swim, and a tank that allows it to grow to its full potential.

Remember, the aquarium you invest in becomes a lifetime home for your little pet. Make sure you purchase one that gives your fish space and the surface area it needs to stay happy.

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