Best 20 Gallon Fish Tank: Tips and Review

If you’re finding a bigger aquarium that still not take much space or be limited as the 10 gal tank, then consider choosing the best 20 gallon fish tank. The beauty of having the best 20 gallon fish tank is that you can keep aggressive and territorial fish. Also, the tank is big enough to provide space for your fish to grow and still be happy.


Marina LED Aquarium Kit 20 gallon

Marina LED Aquarium Kit

4.2 of 5 Stars
GloFish Aquarium Kit Fish Tank with LED Lighting and Filtration Included 20-Gallon

Aquarium Kit Fish Tank with LED Lighting and Filtration Included

3.8 of 5 Stars
Aqueon Led Aquarium Kit 20h Black 20 Gallon

Aqueon Led Aquarium Kit 20h Black 20 Gallon

3.9 of 5 Stars

5 Tips to Create Best 20 Gallon Fish Tank

1. Pick the Best Fish for 20 Gallon Tank

Some of the best freshwater fish for 20 gallon tank include molly, cory catfish, zebra danio, and swordtail fish among others. If you have aggressive fish then consider also getting a 20 gallon fish tank stand so you don’t find your fish swimming on the floor.

In case you want a 20 gallon long reef tank, consider shrimp, porcelain crab, clownfish, firefish and Wetmorella to go easier.

Via YouTube: My Top 7 Best Aquarium Fish For 20 Gallon Aquariums

2. How Many Fish in a 20 Gallon Tank Are Needed

Blue neon tetra| 20 gallon planted tank

Blue neon tetra love to live with their species in a 20 gallon planted tank

A 20 gallon fish tank will provide more space for your fish but is not big enough to serve every fish you want. Therefore, you should figure out the reasonable quantity of each type of fish to have a healthy aquarium.

Basically, people choose the number of fish keeping in a 20 gallon water tank by the rule of “One inch per gallon” when it comes to small fish, which means every gallon of the tank can serve for one inch of a grown fish.

E.g. How many tetras in a 20 gallon tank is suitable? Tetras love to live in school of at least 5-6 fish. You should only keep them with other peace types, and especially in a 20 gallon planted tank. A grown Neon tetra has the max length of 1.5 inches so you can keep 13 – 14 of them in a 20 gallon fish tank.

3. Should I Choose a 20 Gallon High or Long Tank

Between a 20 gallon long aquarium and a 20 gallon tall aquarium, a high tank will be better if you want to build a community with many fish layers, while the long tank is more suitable if you only deal with the substrate, horizontal swimming fish, or need more space above the tank.

A 20 gallon long tank has the height of 12 inches, so it would be a choice for small quantity of bigger fish, but both it and 20 gallon tall fish tank should be stocked with small fish for the best result.

20 gallon tank dimensions

20 gallon fish tank dimensions

4. Which is the Best 20 Gallon Fish Tank Material

20 gallon acrylic tank and glass tank are the most popular material. Using acrylic as tank material supports lots of well-designed aquariums, like a 20 gallon hexagon fish tank, for example. Tank made from acrylic will offer a clearer vision, longer durability, and less weight than a glass tank. 20 gallon fish tank weight of acrylic is only half of a glass one (material counting only).

In the other way, glass tank is hard to be scratch, and it will not go yellowish after time as the acrylic fish tank. These glass aquariums also cost lower in purchasing, shipping, and fixing problem. You can look for more support from glass tank without using a complete cover while putting it on a 20 gallon fish tank stand.

Via YouTube: 20 gallon acrylic aquarium vs. glass aquarium

Each type of material has its own pros and cons, if you go with affordable price and easy maintaining, choose a glass fish tank; or else, pick a 20 gallon acrylic aquarium to have awesome visual and high durability.

5. Prepare for Best 20 Gallon Fish Tank Set-Up

best 20 gallon fish tank filter and heater

Picking best 20 gallon fish tank filter and heater to maintain your fish healthy

20 gallon fish tank filter

Finding the best filter for 20 gallon tank is the first thing you should care. We suggest you choosing between a power, canister or internal filter.

20 gallon undergravel filter is an option, but not the best 20 gallon aquarium filter because you must clean it more often, know how to use it properly, and it’s probably not work for a reef tank.

Better choosing a 20 gallon fish tank filter that helps you work easily with every filter media: mechanical, biological, and chemical filtration, like the Aquaclear 20 power.

20 gallon fish tank heater

Choose an aquarium heater to maintain the needed temperature for your fish growth. Besides, a thermometer will help you check the temperature more precisely in case the heater is malfunctioning.

20 gallon fish tank stand

Glass tanks need a strong stand to bear its weight, and acrylic tanks require a fit stand to support its bottom structure.

20 gallon aquarium hood and light

There are lots of 20 gallon long hood and light available on the market. They provide natural light and prevent water lost, which is good for both fish and aquatic plant. For a tall aquarium, you need a more powerful 20 gallon fish tank hood and light to make sure it lights up the whole tank.

Decorating items

It would be easier for you to decorate a 20 gallon tall fish tank than a long aquarium. You can add in plants, corals, diverse substrates such as sand, gravels, etc. to create a beautiful background.

Best 20 gallon fish tank reviews

1. Marina LED Aquarium Kit

Marina LED Aquarium Kit 20 gallon

Marina LED Aquarium is tailored to cater for both beginner aquarist and the experienced ones. The design of the tank is very simple, and the parts are easy to assemble. It is made of high-quality glass that is hard to scratch. Since it can be a hustle getting or the necessities to start an aquarium, this tank comes with all the essentials you need.

It is vital to keep your aquarium clean at all times. The Marina LED Aquarium contains a Marina Slim S20 clip-on filter. The quick-change filter cartridges make it easy to clean and replace the filters. The technology allows for biological filtration, which is plus in keeping your water conducive for the fish.

The long-lasting LED lamps that mimic the daylight are fixed on this 20-gallon fish tank lid.



Our rating


  • The kit contains almost everything you need to start up the aquarium.
  • The glass aquarium is easy to clean.
  • The LED lamps are fair.
  • The filter cartridges are easy to clean and replace.


  • Water trickles down the filter.

2. Aquarium Kit Fish Tank with LED Lighting and Filtration 

GloFish Aquarium Kit Fish Tank with LED Lighting and Filtration Included 20-Gallon

Deciding whether to get a 20-gallon acrylic aquarium or glass aquarium can be easy. For most people, the filtration system, lighting, and material of the aquarium are what determines a deal from a deal-breaker. However, there are additional features that bring that natural habitat feels that is also important. The GloFish Aquarium Kit comes fully loaded with all essentials such as food, water treatment sample, and user manual.

However, the extras are what caught our eye. You get GloFish yellow anemone and 3 GloFish plants to add that natural look. The blue LED light stick provides ample lighting while Tetra Whisper 20 filter does all the cleaning to make sure the water is safe.

 We found the filter to be very effective and silent. The kit also comes with a Tetra mini UL heater to provide constant water temperature if you are keeping tropical fish.



Our rating


  • The glass tank is easy to clean.
  • The GloFish kit comes with all the essentials plus extras.
  • It comes with a heater.
  • The Tetra Whisper 20 filter is silent.


  • The LED lights are only blue

3. Aqueon LED Aquarium Kit 20H Black 20 Gallon 

Aqueon Led Aquarium Kit 20h Black 20 Gallon

The best aquarium is the one that blends well with your interior design. It is more serene when an aquarium feels like part of the home or office. The Aqueon aquarium kit contains everything that you need to make your fish feel like they are back in the wild. The Aqueon, 20-gallon aquarium, is made of glass for enhanced visibility and smooth cleaning.

The rectangular-shaped tank comes with a 20-gallon aquarium hood that has cool white LED bulbs installed. The LED light frequency is right to make your fish feel at home and brighten up the aquarium.

It is easy for debris and other waste to accumulate in an aquarium. The Aqueon aquarium is powered by a 20-gallon filter to help you keep the environment safe for your fish. Its filtration system consists of an Aqueon QuietFlow LED PRO filter that has a red LED indicator to show when it’s time to change the cartridge.

The cleanness of your aquarium is guaranteed by the ammonia filter pad and the five-stage filtration system. This tank is perfect for tropical fish because it comes with a 78 degrees preset heater.



Our rating


  • It has pre-set heater included in the kit.
  • The ammonia filter pad helps with filtration.
  • The filter is relatively silent.
  • The kit comes with all the essentials and user manual.


  • The LED bulbs do not have splash guards.
  • The heater is functional but not efficient.


If you are a beginner, get yourself a best 20 gallon fish tank kit to save more time and effort to own a wonderful aquarium. No matter you choose a reef tank or a freshwater tank, a medium size – 20 gallon fish tank is not too hard for you to create and maintain it.

Think about a stunning aquarium with bunches of lovely fish swimming around will be a motivation for you to start your own best 20 gallon fish tank right away. Let’s work and we are here ready to help you in any stage of your fish raising journey.

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