If you’re a beginner aquarist then having a big aquarium can be quite hectic as there are lots of maintenance required. 20-gallon fish tanks are a blessing for the beginners as they are super easy to maintain and offers a lot of possibilities.

20-gallon aquariums are a perfect choice for both professional and beginner aquarists. Despite the small space, it enables you to keep tons of aquatic species. It gives you plenty of spaces to keep the fishes while being easy to maintain.

In this article, we’ll be reviewing the best 20 Gallon Fish Tanks so that you can make the best decision while making the purchase.

Our Top Picks | Side By Side Comparison

  1. Marina LED Aquarium Kit
  2. Tetra 20 Gallon Complete Aquarium Kit
  3. Aqueon Aquarium Fish Tank LED Kit
  4. SeaClear Acrylic Aquarium Combo Set
  5. Marineland Biowheel Aquarium Kit
  6. Glass Aquarium 20 Gallon
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Reviews of Best 20 Gallon Aquariums

1. Marina LED Aquarium Kit

Marina LED Aquarium Kit

The Marina LED Aquarium Kit is one of the top-rated aquarium kits in the market that comes with a unique design and a hygienic environment. It provides an ambient environment for the aquatic species where they can flourish and live a healthy life.

Marina LED is hands down one of the best 20-gallon tanks there is. Setting up this aquarium kit is super easy as it comes with a clear instruction manual. It made with high-quality material that enables it to provide the best environment for the fishes.

It has a dimension of 24″ L x 12.5″ W x 16.5″ H. It’s made with top of the line long-lasting glass body with a natural LED light that’s incorporated in the canopy. This tank helps to keep a clean and healthy environment with just a little maintenance. This kit includes Marina Slim S20 clip-on filter along with quick-change filter cartridges for easy operation and maintenance.

It’s important to create a favorable environment so the fishes can enjoy a long healthy life. The kit comes with Fluval Cycle biological supplement and Fluval Max fish food so the fishes can stay at their best health condition.

  • Made with long-lasting glass
  • Natural LED lighting
  • Fast changing filter cartridges
  • Include fish food and supplement
  • Hassle-free maintenance
  • Clear manual guideline
  • The LED light isn’t long lasting

2. Tetra 20 Gallon Complete Aquarium Kit

Tetra 20 Gallon Complete Aquarium Kit


Aquarist all around the world rave about the Tetra 20 Gallon Fish Tank Kit and they only have to say good things about it. It’s an overall aquarium kit that comes with plenty of amazing features.

The Tetra 20 Gallon comes with a tank that has a dimension of 24.2″ L x 12.4″ W x 16.7″ H. The tank size is perfect for having a number of small fishes and aquatic species.

The tank is made with long-lasting scratch-proof glass that’s made to last. There’s an LED hood that mimics the daytime effect to provide the fishes with a more natural environment. As we said earlier that it’s a complete kit, so, it also includes heater and filter so that you can set it up right away.

It includes a Whisper Filter that has whisper quiet operation. It effectively cleans the water and creates a nice healthy environment where the fishes can thrive. It includes artificial plants which give the fishes a homely feeling as they can hide and play to reduce stress. You’ll get four artificial plants along with gravels to make it as ocean-like as possible.

  • Simple set up procedures
  • Comes with filter and heater
  • Spacious
  • Includes artificial plants and gravel to create an ocean-like vibe
  • The LED light gives a natural daytime effect
  • The filtration system doesn’t offer 3-stage filtration

3. Aqueon Aquarium Fish Tank Kit

Aqueon Aquarium Fish Tank Kit

The Aqueon Aquarium Fish Tank Kit is another superb 20 gallon fish tank that makes others a run for their money. This aquarium kit is a great addition for both beginners as well as experts. It comes with a number of features that will give any aquarist an amazing experience.

This filter has a dimension of 2 x 12.5 x 19.5 inches with a weight of only 5 pounds. It’s made with extremely durable glass material that’s will surely last you a while. It has an LED light which is fixed in the canopy. The light provides the optimum amount of brightness that gives an aquatic vibe to the fishes and other marine species.

This fish tank is not a suitable option for the people who are willing to keep cold water fishes as it comes with a preset heater that will keep the temperature constantly at 78 degrees. The heater is perfect for keeping most tropical fishes as it offers a suitable environment for them.

It also includes high-quality QuietFlow 10 LED PRO power filter with a medium cartridge. The filter has a red LED light that will flash when it’s time to change the cartridge.

  • Comes with high-quality filter and heater
  • Includes premium fish food, water conditioner, and fishnet
  • The LED light creates a favorable environment for the fishes
  • Easy to install
  • Stick-on thermometer to measure temperature
  • The heater is preset at 78 degrees so not suitable for cold water fishes

4. SeaClear Acrylic Aquarium Combo Set

SeaClear Acrylic Aquarium Combo Set

If you’re looking for a reliable acrylic aquarium then think no more and get your hands on the SeaClear Acrylic Aquarium Combo Set. It’s a great addition for the aquarists who prefer a clear view of their tank. It’s an extremely durable tank that offers an incredible view of the marine creatures.

The tank has a dimension of 24 x 13 x 16 inches which provides enough room for the fishes to roam around. Acrylic is way clearer than glass with seventeen times more durability. The best part is, even though it comes with incredible durability it’s a lot lighter than glass or other material.

Since the SeaClear is made with high-quality acrylic, it’s suitable for both saltwater and freshwater fishes. It’s extremely impact resistant and scratch-proof which makes it suitable to keep around children and pets.

However, unlike other kits that we reviewed earlier, it doesn’t come with filter, heater or any sort of decorative pieces. The filter, heater and other equipment need to be bought separately. Also, there’s no built-in LED light with this set. However, the lid has a 15″ reflector where you can set up the lightening system.

  • Extremely durable
  • Scratch-proof and lightweight
  • Weighs less than glass
  • Offers a crystal clear view inside
  • Impact-resistant
  • Doesn’t come with heater, filter or any other kit
  • No LED light

5. Marineland Biowheel Aquarium Kit

Marineland Biowheel Aquarium Kit with LED Light

You’re probably wondering what is the difference between Biowheel aquariums and regular aquariums? Well, biowheel provides a superior biological filtration system that effectively removes any sort of toxic substances inside the tank.

Biowheel cleans up all the traces of ammonia and nitrate that are harmful to the fishes and create a clean environment for the fishes. The filter has spinning wheels that offer top of the life filtration.

This kit includes a hood with LED lighting, a submersible heater, fishnet, premium quality fish food, a thermometer, water care sample, and a setup guide. The hood top can be easily opened to provide food to the fishes and for cleaning purposes.

The best part is that this aquarium requires little to no maintenance. As it comes with a high-tech filtration system, it mostly self-cleans itself. The LED lighting has three different settings available so that you can pick the setting that suitable for the fishes you’re keeping. The LED light can mimic both daytime and nighttime environment.

It includes premium quality food that provides a nutritious wholesome meal to the fishes. Also, the fishnet and decorative pieces create a favorable atmosphere where the fishes can live a healthy playful life.

  • High-quality Biowheel filter
  • LED light with multiple settings
  • Comes with submersible heater, fish food, and thermometer
  • Little to no maintenance required
  • Slightly expensive

6. Glass Aquarium 20 Gallon

Aquarium Tank Glass 20 Gal

If you’re looking for a simple 20 gallon fish tank with incredible durability then get your hands on the Glass Aquarium 20 Gallon. It comes to a very affordable price tag so it’s a great option for the people who are on a budget.

This tank has a dimension of 30″ L x 12″ W x 12″ H. The long length provides more space for the fishes which enables them to easily swim across the tank. It is suitable for both saltwater and freshwater fishes.

It’s made with extremely durable glass that will surely last a long time. The company offers 100% satisfaction guarantee and you can always ask for a refund if you’re not satisfied with the performance of the product.

Bear in mind that the tank doesn’t include filter, heater or any other equipment. All the necessary equipment should be bought separately. However, it’s compatible with most of the aquarium devices so you’ll not have any trouble finding the suitable equipment for it.

As the tank has a longer length than other regular tanks, make sure you buy an appropriate hood which matches its length. The length of the tanks is 30 inches so get a hood slightly bigger than that so it gets covered entirely.

  • Affordable
  • Long length offering more space to the fishes
  • Durable
  • Lightweight
  • 100% satisfaction guarantee by the manufacturer
  • All the equipment need to be bought separately
  • Doesn’t come with a hood

Things to Consider before Purchase: Buyer’s Guide

Only knowing about the best 20 gallon fish tanks isn’t enough. There are a number of factors you should consider before making the ultimate purchase. It’s essential to consider all these factors to make the best out of your decision.

best 20 gallon fish tank

Water To Put in the tank

The condition of an aquarium relies immensely on water. The supply water is quite different than natural or river water as it contains lots of chemicals. Fishes can thrive in river water or ocean as long as the surrounding compound matches with their needs. Make sure the supply water you put in the aquarium is properly filtered and don’t contain chemicals like chlorine, chloramine which might harm the fishes. Read this to know more about aquarium water treatment.

You should also have the tank water properly cycled before introducing any fish.

How Many Fish For A 20 Gallon Tank

20 gallon aquariums are of moderate size and you shouldn’t keep too many types of fishes at the same time. If you’re beginners, it’s always better to start with a single species and increase the number as you gather more experience.

A 20-gallon tank can hold about five to seven fishes with the size of five to seven centimeters easily. You can put more than that, however, it’ll seem too crowded. You need to keep space in the tank so that the fishes can move freely and live a healthy life. If the fish is tiny like amber tetra or celestial pearl danio then you can put around 20 of them in a 20 gallon tank.

Bear in mind that an overly crowded tank with too many fishes will hamper the growth of the fishes and eventually put their lives in danger. Also, big fishes tend to eat the little ones so it would be a bad idea to keep them together. Always check the fish compatibility chart before adding new species.

Temperature To Maintain

There are some tanks that come with a preset temperature setting. Often time these temperatures ratings are high and they are not suitable for the cold water fishes. If you buy a tank for cold water fishes then make sure the heater isn’t preset and if you buy it for the tropical fishes make sure it’s suitable for them to thrive. Use an external thermometer to keep a close eye on the temperature.

Proper Filtration in Place

Filtration is one of the most vital aspects that you should focus on when you’re keeping aquatic species. It’s extremely important that the tank is properly filtered so it is clean and safe from all sorts of toxic substances like ammonia and nitrite.

It’s crucial that the harmful chemicals and fish wastes are properly removed so that the fishes don’t have to live in an unhealthy environment. There are several tanks we reviewed that comes with its own filter, in some you have to buy the filter separately. No matter what kind of filter you opt for, make sure it does the job properly to keep the fishes safe and healthy.

Lights For the Tank

Aquarium lights have multiple purposes. The lights help to mimic the daytime or nighttime condition to the fishes and they also help to see you the color of the fishes better. The light will create an atmosphere which is similar to their natural living place in the wild. Thus, helping them lead a happier and healthier life.

Proper light is also very important if you want to grow aquatic plants in your tank. A 20 gallon tank is almost perfect to create a wonderful aquascape.

Hood For the Tank

Fish tanks generally come with a hood to cover the top part. All the fish tanks that we reviewed features a hood of its own except for the Glass Aquarium 20 gallon fish tank. Try to get a fish tank with its own hood. However, if the tank doesn’t have the hood make sure the hood you buy is compatible with the tank and fits perfectly.

What are the Fishes Suitable for a 20 Gallon Fish Tank?

20-gallon fish tanks have a moderate size so you can keep almost any small fish. It gives you a wide array of possibilities and you can keep a number fishes in these tanks. Make sure the fishes don’t grow too big as the bigger fishes sometimes eat the smaller ones. Also, the fishes you keep should be able to live in the same water condition.


platy fish

Platies are super attractive to look at and they are super active as well as fun to watch. Being a small fish, Platy is a perfect match for 20-gallon fish tanks. Try to keep two females for every male to keep a balance between them. You can distinguish between the genders by looking at the fin under their belly. If the fin is wide and flat then it’s a female and if it’s pointy then it’s a male.


Corydoras are an excellent option if you’re looking for a bottom-feeding fish. They are small in size and fun to watch. These little guys will also help you keel the tank clean as they eat leftover fish foods that lay at the bottom of the tank. These are shoaling fish so it’s better if you keep them in a pack of at least four to six.

Dwarf Gourami

Dwarf Gourami is a beautiful fish with excellent color but bear in mind that they are a little aggressive. The aggression isn’t mostly shown, however, to avoid any mishaps, don’t keep two male in the same tank as the pair may induce a fight or bully each other.


Swordtails are a lot like platies both in behavior and looks. They’re a bit slimmer and longer in size than the platies. Like platies, keep one male for every two female to keep a balance among them. Male swordtails are very easy to identify as they have a long sword-like tail.

Fancy Guppies

fancy guppy

Guppies are a must have for every aquarium. Fancy guppies are one the most elegant and colorful fishes you can have in your tank. As they are tiny, they will not occupy much space in the tank. Fancy guppies are an absolute treat to the eyes and they’ll surely increase the grace of your 20-gallon tank.

Harlequin Rasbora

These little munchkins are absolutely mesmerizing and they’re peaceful community fish. These should be kept in a pack of at least six and they’ll be a perfect addition to your 20-gallon tank. However, make sure you don’t keep large fishes in the same tank as those will eventually eat these babies up.


Along with fishes, you can also consider keeping critters in your 20-gallon aquarium.

African Dwarf Frogs

African Dwarf Frogs are very adorable to look at and they are an outstanding fit for 20-gallon aquariums. However, having a frog would be quite some work and we don’t recommend it if you’re a novice aquarist.

With the pack of fishes around, it will be tough for them to compete for food. Ensure that there’s enough food for them and include a variety of meals such as sinking pellets and algae wafers along with flakes and other fish food.


Shrimps are also a very common critter to keep in 20-gallon fish tanks. Ghost shrimps are one of the most common shrimps that can thrive in the aquarium environment. They’re quite inexpensive also have low bioload impact.

Like Corydoras, these will also help to keep the tank clean. You can also opt for cherry shrimps as they have an excellent appearance. Make sure you don’t have large fishes around them otherwise, they’ll become their lunch in no time.


Snails will help to clean the algae in the tank and also feed on the leftover fish food. However, they are not an ideal choice if you have a planted tank as they will eat up the live plants. Apple and mystery snails are a perfect fit for 20-gallon fish tanks.

Wrapping Up

Finding the right tank is quite a daunting task as so many variants are available out there. 20-gallon fish tanks offer a versatile option for both beginners and advanced aquarist. You can keep a number of small fishes and plant and create marine heaven of your own.

We have reviewed the best 20-gallon fish tank available out there so that you can get the best value out of your purchase. There are many factors to consider so we have incorporated as much information as possible so that we can give you a detailed idea on the fish tanks.

So get the tank that matches your requirements and budget to have some quality time with your aqua buddies.

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