Best 20 Gallon Long Aquariums (Stocking Ideas, Equipment and More)

20 gallon long aquariums are wonderful tanks that combine everything both experienced and amateur aquarists crave.

It is wide enough to accommodate most setups and has just the right amount of space to become a great home for many beautiful fish.

Deciding which is best tank for you (especially for the first time) can be hard, but 20 gallon aquarium tends to be a universal choice that will rarely leave you disappointed.

Does this sound like something you are looking for?

In that case keep on reading to learn everything about possible setups, our favorite tank selection and lots more…

Best 20 Gallon Long Aquarium

Aqueon 20 Gallon Long Tank
Aqueon 20 Gallon Long Tank

This aquarium is made from high quality glass and can be used by beginners and experts for a wide range of tanks.

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Aqueon are well known within the aquarium industry for producing high quality fishkeeping equipment – the Aqueon 20 gallon long tank is no exception.

Made from glass, this tank is suitable for both marine and freshwater setups. It can be used as a show tank, a breeder tank or a species only tank.

The edges are sealed with a clear silicone, and the trim is available in either black or oak depending on your preference.

This tank comes with a 90 day warranty, and measures 30.2 x 12.5 x 12.8 inches.

Pros:
  • It can be used for a wide range of purposes.
  • Quality construction and well made.
  • Tank only package so you can choose your preferred equipment you.
  • Gives you slightly more space lengthways than an regular 20 gallon tank.
Cons:
  • It’s quite expensive.
  • If you are a beginner you might find it hard to choose equipment.
  • The sealant is a little messy.

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20 Gallon Long Aquariums Overview (101)

20 Gallon Long Aquarium

A 20 gallon tank is a wonderful compromise for people that want something in between a large and small aquarium.

This compact tank can be used for both breeding and keeping, so unsurprisingly a 20 gallon long tank is most people’s go-to choice.

These tanks are large enough to create an amazing aquatic environment, including a diverse array of plants alongside lots of pretty fish. It does not matter whether you would like to keep a marine or freshwater environment, there is enough space for each of them.

This tank can also be home to a number of invertebrates, including: shrimps, crabs, and even some smaller turtles. As long as you are considerate of their requirements, you can even keep them together.

Whether breeding or keeping, the size of the fish ultimately determines the volume of the tank.

Generally, most fish that are larger than 2.5-3 inches will require a tank that is bigger than 20 gallons. However, this tank makes up in length what it lacks in sheer volume. You can comfortably accommodate plants alongside your fish while still maintaining a safe and healthy environment.

If you are planning on breeding fish, the 20 gallon long aquarium is definitely a tank you can consider.

It really comes down to the fish you want to keep, your budget and flexibility.

As for additional equipment, this tank falls right in the middle of two categories. Although quite large, there still isn’t much need for a bulky filter and you will be best off using a simple internal adjustable filter, the same goes for the heater (more on this later).

Aquarium Masters 20 Gallon Long Aquarium
Aquarium Masters 20 Gallon Long Aquarium

This diamond polished edged, distortion free tank is made with high quality materials and exceeds industry standards, perfect for beginners or experts with a wide range of uses.

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20 Gallon Long Aquarium Dimensions

A 20 gallon long tank will have a base that is slightly longer than regular 20 gallon tanks.

Usually they will measure 30 inches in length, and 12 inches in width and height (30x12x12 inches).

However they can slightly vary in size from model to model – whilst the volume itself will be the same, the dimensions of the tank (L x W x H) can differ.

20 Gallon Long Fish Tank Equipment

20 Gallon Long Equipment

In a tank this size you will need some basic equipment.

We are going to walk you through the equipment that most tanks of this size will need and also give you our top picks too.

Filter

Aqueon QuietFlow Power Filter
Aqueon QuietFlow Power Filter

This self-priming filter is easy to setup and use, and provides all three necessary filtrations for your setup. It’s perfect for a 20 gallon long tank.

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The filter is an essential piece of equipment for every tank. If there is no filter, then there is no circulation.

Without circulation, there is no active nutrient or dissolved oxygen cycle – these components are crucial for the development of any aquatic animals.

Apart from creating a healthy environment, a quality filter can significantly aid in breeding by creating a current in the tank. Some species also need a stable permanent flow to stay healthy and reach maximum length – in long tanks this is even more important.

The best choices for a tank of this size are HOB or external filters.

Heater

Tetra Submersible Heater
Tetra Submersible Heater

This affordable heater is small and has a built in thermostat to help maintain the temperature of the tank at 78°F.

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Keeping the tank temperature within an acceptable range is just as important as filtration.

All organisms feel best at a particular temperature. External temperature plays a key role in the life of aquatic organisms because fish cannot regulate their own temperature.

So the heater choice will be determined by your aquarium inhabitants. Make sure that all of your fish can live comfortably at the same temperature or at least can tolerate the same temperature range.

Then get a heater which is capable of maintaining the required water temperature. For a tank this size about 150-250W will be fine.

Stand

Imagitarium Metal Stand
Imagitarium Metal Stand

This 30 inch stand is perfect for a 20L aquarium, it will fit in well in most homes with a simple black finish.

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Although they are not absolutely required, aquarium stands are a nice addition to any setup. It will add additional stability to the tank, avoid scratches on furniture and can also help to keep the aquarium warm.

Given that 20 gallons tanks are not that big, their stand should not be either.

You will be able to fit one into your room without any problem. It will also probably have space inside to store other equipment, food and any plumbing.

Hood and Lights

MarineLand LED Light Hood
MarineLand LED Light Hood

Fitting most 20 gallon long aquariums perfectly, this hood features sleek LED lighting which is integrated into the hood even when open.

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Lighting in the aquatic world is as important as temperature and filtration.

Fish rely on the day-night cycle to regulate many vital functions. If their light regime is disrupted, it will impact the health of your fish and negatively impact their lifecycle.

To avoid excessive plant growth and at the same time keep fish healthy, aquarists use hoods and aquarium lamps. Aquarium lamps imitate natural sunlight, while providing just enough lighting to encourage the growth of plants.

Hoods are used to limit the amount of direct light. This comes in really handy during breeding periods when fish may need a dimmed or a completely dark environment. Hoods also prevent fish from leaping out of the tank.

There are a good number of different lamps (LED, luminescent, etc.) and aquarium hoods (transparent, mesh, etc.) available. Each combination will suit a different purpose, however most setups use an LED lamp with a solid, semi-covered lid.

Best Fish For 20 Gallon Long Tanks

Guppies

Thankfully this aquarium is perfect for majority of the most popular fish.

You can take advantage of the long base, as it allows you to keep slightly larger fish or, alternatively place more impressive decorations.

Before choosing what fish to place in the tank, carefully check individual requirements and compatibility. The majority of smaller fish can be comfortably kept in this tank in small schools.

Generally you can keep fish that grow up to 3 inches in length, as long as they don’t require plenty of open swimming space.

Some fish you might consider include: Guppies, Swordfish, Barbs and Danios. Other favorites include: Gouramis, Figure 8 Puffer Fish, Dwarf Pufferfish and Betta Fish.

You may also consider Tetras, such as Neon Tetras, Cardinal Tetras and the Black Neon Tetra, or Loaches such as the Kuhli Loach.

Elongated tanks are ideal for bottom-dwelling fish, including fish from the genus Corydoras, Platydoras or Mystus. You can use the length of the tank to your advantage and create wonderful aquatic forests, and your catfish will help keep it clean.

Once again, when picking fish remember that, although the volume allows it they might not be ideal neighbors to each other.

If this is not accounted for, your fish will end up attacking each other and creating a hostile atmosphere in the tank. This can all be avoided by being a bit cautious with your stocking.

20 Gallon Long Aquarium Setup Ideas

20 Gallon Long Aquarium Setup Ideas

This tank is perfect for a range of different setups including: paludarium, marine, freshwater, species-only, community and even a breeding tank.

Let’s first look at the most popular choice, the community setup. This wonderful option allows you to showcase many beautiful fish at once, filling your aquarium with all colors of the rainbow.

In order to build a community tank, you would carefully need to consider individual requirements of every fish and compare them to each other.

Here is one setup you might want to consider: 3-4 Guppies, a pair of Zebra Cichlids, one Cory, such as a Corydoras paleatus, and a shoal of beautiful Rainbowfish or Tetras to add a splash of color.

The decorations and plants you include are also entirely up to you – just make sure to keep 2/3 of the tank free of ceramics and other artificial decorations.

Another very popular setup choice is a species-only tank. The extended base of this 20 gallon aquarium means that you can keep fish such as smaller Acaras, Danios or Shrimp.

If you have always been fascinated by any particular species, this setup will allow you to embrace this passion. This tank has enough volume to create a striking underwater environment to compliment the fish’s appearance. You may even consider getting some artificial corals to maximize shock value.

How to Set Up Your 20 Gallon Long Aquarium

Now we get to the most exciting part, assembling the tank and seeing it all come together.

Setting up this 20 gallon tank is not a difficult task.

You should start off by laying out the substrate. Make sure that the substrate is nicely rounded and distributed well across the base. If you have a undergravel filter (although in the case of 20 gallons it’s unlikely) make sure to read the instructions first and install it.

After the substrate is in place, it’s time to place the plants and decorations. At this point ensure that everything you put in the tank is safe to use in aquariums. Try combining artificial decorations with rocks and plants to create a realistically looking habitat.

When all the decorations are in place, you will need to install the equipment. Every piece of equipment comes with instruction on how to install them and with a tank this size it should not take you long.

After that is all done, you can start filling the tank up with water and apply the necessary chemicals (water conditioner, salt, etc.). Once the tank is full you can turn your equipment on.

Give your tank to complete a full cycle, (4-6 weeks), to allow a bed of beneficial bacteria to build up which will deal with all the harmful compounds in your tank.

You can then add your fish.

It’s a good idea to place the bag with the fish in the aquarium water for 20-30 minutes, so it adjusts to the tank temperature and does not become stressed.

For more help read our complete guide here.

Summary

Aqueon 20 Gallon Long Tank
Aqueon 20 Gallon Long Tank

This aquarium is made from high quality glass and can be used by beginners and experts for a wide range of tanks.

Check On Amazon

A 20 gallon long tank lets you experiment with many different setups.

It has just enough space to accommodate everyone’s needs – you can keep lots of beautiful small fish in this tank. You can also use it as a breeding tank.

Whatever it is you are after, this tank won’t leave you disappointed.

It can accommodate plants, fish, decorations and other animals without taking up much space.

Have you had a 20 gallon tank before? Let us know in the comments section below…

Robert Woods Portrait
Robert Woods is the creator of FishKeeping World, a third generation fish keeper and a graduate in animal welfare and behavior. He is also a proud member of the Association of Zoos and Aquariums, the Marine Aquarium Societies of North America and the Nature Conservancy.

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