How Do I Know the Size of the Fish Tank I Need?

As a guide, a 10 to 20 gallon fish tank set up is generally suitable for 1 fish and you should allow 10 gallons for each additional fish.

What you need to know about fish tanks

1. Buy an tank with the greatest amount of surface area. This is where water meets the air. Goldfish would rather swim further (width-wise) than deeper.

2. A longer tank provides more surface area, giving the option of supporting more fish.

3. A deeper tank means the water won’t be as well aerated.

4. The number of fish you want to keep directly affects the size tank needed.

5. Choosing the best goldfish tank is just as important as choosing your fish. There are many types and sizes of fish tanks and the right choice best makes a big difference to the health of a goldfish.

If you have a 10 gallon fish tank setup don’t forget filtration is still needed to control ammonia levels

Why is tank size important?

1. To keep a goldfish healthy and happy, they need a clean environment with plenty of room to grow. To the surprise of many people, a 10 to 20 gallon goldfish tank is really only sufficient for 1 goldfish. Adding another 10 gallons per fish is ideal.

A 55 gallon tank setup is a popular choice. If you have room, you can set up an interesting aquatic environment with different types of goldfish that interact socially with each other.

2. Goldfish are dirty fish, and it’s important to keep the water quality as high as possible.

3. Providing fish with larger tanks can reduce the potential for parasites and disease.

4. Fish waste and uneaten food causes ammonia levels to rise in the water. Elevated ammonia levels can cause burns and infections in goldfish. It’s easier to clean the waste out a large tank with a small number of fish. This helps keep ammonia levels at a minimum.

5. Goldfish can live for many years and reach their full potential if properly housed in a big enough tank.

6. Small containers are suitable for a brief time only. It’s true that fish grow to the relative size their environment allows but this is not ideal. Give your pet plenty of space to swim around.

7. You’ll probably want to add aquarium plants and other items like a filter and air stone, gravel, perhaps algae eaters as well. Allow space to make your tank interesting, and healthy for your fish.

8. This is an equation to remember: the smaller the quantity of water in the aquarium, the quicker the water will evaporate. You’ll need to top up the water in a small tank regularly, especially in warmer weather.

Water testing kits to test the ammonia and other toxin levels in the water are available. The kits are helpful to keep water at a balanced level.

How many goldfish can live in a 10 gallon tank?

It’s an often asked question but a 10-gallon tank is only suitable for 1 goldfish. It’s not ideal for the fish to stay in this size tank for long.

People sometimes start off with this size and as they get more interested and learn more about goldfish step up to a larger size. 10 gals is a useful size because it can then serve as your isolation or ‘hospital tank’. If you have a sick fish, or even suspect a fish is not well, you can isolate it from the rest of the fish in your tank. This stops disease spreading to other fish and you observe and treat your sick fish separately.

10 gallon tank dimensions

20″ x 12″ x 10″

20 gallon fish tank size

There are 2 20 gal aquariums sizes considered standard. Either 24″ by 12″ by 16″ (high) or 30″ by 12″ by 12″ (long).

What's the best material?

Glass still remains the best material. Numerous synthetic materials have been used to make inexpensive aquariums.

Glass is the best choice and these are the reasons why.

It gives good clarity
Glass will last for many years
It’s easily cleaned
Glass tanks are attractive and sturdy making them a great home for your goldfish.

An aquarium that’s made from all glass and is well sealed when manufactured should last a lifetime. Don’t take chances. Buy a tank made of good, strong material.

Choosing the fish tank shape

Shape is an important decision. This is because the better aerated the water the more fish you can comfortably house. There are shape and form options available. For example tall, hexagonal, round, square…you get the picture.

These different shapes might be interesting, but by far a rectangular tank is the most popular. Here’s why

The shape is very practical and gives an excellent frontal viewing area
It has a first-class surface area in relation to water volume (a very important point as far as stocking levels go)
Because of its capacity and proportions, the rectangular shape works well for additional equipment you need: filters, pumps, decorations, etc. Good ventilation is provided with auxiliary or additional equipment and this makes the goldfish environment much more pleasant.

Tanks that are round in shape provide an irregular or distorted view of your fish. Triangular-shaped will not house the number of fish that the frontal area might suggest.

Tall aquariums have a poor surface-to-volume ratio and maintaining good aeration can be a nightmare because it can only be achieved with ancillary equipment. They’re just very impractical units, especially for coldwater species.

If you decide to buy a cheap aquarium, keep in mind they’re likely to be defaced when cleaned and will turn yellow with time and use. They’ll also curve or arch more easily and you’ll have problems with the bigger ones if the materials used to make the tank are cheap.

Other construction material

In the past fish tanks were often made from synthetic compounds such as plexiglass. These inferior materials were used to keep costs low, but they scratched easily and became yellow with use. The acrylics available now are better quality but to buy a tank that’s higher quality is more expensive.

Heavy, metal-framed tanks or goldfish bowls are sometimes chosen. Often it’s because people are not made aware of better options.

Framed tanks were associated with leaking as they rusted. Fortunately this changed thanks to the production of modern silicone bondings and frameless tanks. Although there are still framed tanks on the market, usually the frame is viewed as being ornamental.

Most tanks that are sold today are made of glass and sealed with a silicon rubber cement that’s water resistant and very strong.

Never buy or accept a tank that has any spots that are not caulked with the silicone rubber cement or has scratches. Tanks with these issues will have a tendency to either burst or leak.

Goldfish bowls present problems such as overcrowding. The frontal view may suggest that a larger number of fish should be able to fit comfortably inside the bowl. In reality that could not be further from the truth.

If you want an aquarium that will arguably last a lifetime the all-glass aquarium that’s well sealed when manufactured is recommended. The right materials will make all the difference when it comes to housing your new little family members.

Fishbowls and tanks comparison

There’s lots of reasons why people keep fish in bowls rather than fish tanks. Although it’s logical to think that a fish tank is better for the health of fish, some have been very successful raising fish in bowls. Depending on your situation, it might be necessary.

These are the advantages and disadvantages of each.

Fishbowls

Advantages:

Space saving – People who live in small apartments are usually short on space. Fishbowls are very compact and suitable for cramped spaces.
Money-saver – Typically speaking, fishbowls are more affordable for those who are short on cash.
Mobile – Fishbowls are relatively easy to move around and transport. They are lighter than fish tanks.
Simplicity – Children can take care of fishbowls easily. Great for beginner pet owners and children. (not ideal for fish though)

Disadvantages:

- Limited space – As they age, many fish outgrow their fishbowls. Fish can experience stunted growth as a result of the limited space provided in the bowl.
- Constant water changes – Most fishbowls are too small for a filtration system. Fishbowls have to be cleaned often for the fish to stay healthy.

Fish tanks

Advantages:

Healthy lifestyle – Filters can be used in fish tanks to help keep the water clean for a healthier environment.
Spacious – Fish have more space to swim around and explore. More real or artificial plants and other items can be placed in the tank.
Community – Rather than having just 1 or 2 fish, you can raise a variety of fish at the same time.

Disadvantages:

Higher maintenance – Fish tanks require more maintenance with all the moving parts there are, including filters.
Immobile – Due to the size and weight of fish tanks, they’re generally not moved around very often.
More expensive – Fish tanks and the accessories.

An important point to keep in mind is how big the fish is expected to get when it becomes a full-grown adult. The container used to house the fish needs to be appropriate for the fish to grow.

You need to decide which type of container suits your taste or fits your lifestyle. Both fishbowls and fish tanks can be plain or extremely fancy.

Drum – This is the classic style of fishbowl that’s wider than it is deep. It’s a beginner or child’s bowl.

Round – A fishbowl that’s completely round. For the same size, the round fishbowl has a higher capacity than the classic drum style.

Bio-Orb – This newer style of fishbowl can include filtration systems and lights. They’re generally larger than the traditional drum or round ones

Fancy goldfish bowls – Over the years, people have been creative about the types of bowl they use for their pet fish. Contemporary designs are not limited at all in style.

Fish Tanks – Tanks provide more space for multiple fish to swim around and tend to be less fancy. Traditionally, fish tanks are rectangular.

Here’s some examples of creative, weird and downright wacky bowls and tanks.

Final thoughts on goldfish bowls

Some people decide to choose a goldfish bowl instead of checking out the tanks. A bowl may be a way to save money, but it’s not recommended for goldfish.
Goldfish bowls are very small and don’t allow near enough room for a goldfish to grow properly. They generally don’t have a filtration system or they provide very little filtration. If a bowl must be used, it should be only for temporary housing.
Your fish will live much longer if moved to a goldfish tank.
Always use bigger receptacles to house healthy goldfish. Buy the biggest aquarium that you can afford.

Goldfish can live for many years and reach their full potential if properly cared for in a big enough tank. They need a clean environment with plenty of room to grow and thrive.