7 Best 20-Gallon Fish Tanks – An Extensive Buying Guide

20 Gallon Aquarium Tank
By Garrison Hickles Updated

One of the most popular tank sizes among aquarists, the 20-gallon fish tanks are large enough to host a variety of different species, yet small enough to be accommodated in a small space.  But with hundreds of options available in the market, how do you pick the best 20-gallon fish tank? And what are the aspects that you need to know to understand their functionalities? We take a deep dive into all of these here.

20-Gallon Fish Tank – An Overview

Usually, a 20-gallon tank comes with a kit, which is a great selling point for beginners. You don’t have to worry about which apparatus is suited for your tank, and you also don’t have to scramble your way to go out and purchase equipment separately.

A common myth among novice aquarists is that they think that the smaller the tank is, the easier it is for them to maintain them. This belief couldn’t be any farther away from reality because the smaller the tank is, the quicker the chances are of it getting filled with ammonia and nitrite. This means that small tanks need more frequent water replacement than a mid-sized or large tank.

This is why a 20-gallon fish tank is quite apt because it is neither too small that would require frequent cleaning nor it is too large that might be out of your budget or too big to be kept in the space you want to keep it in.

Try to make sure the tank is rectangular in shape. In other words, if the tank’s length is longer than its height and width, it would give more room for your aquatic pets to move around; thereby making them feel more at home.

Usually, these tanks measure 24x12x16” (60x30x40 cm).

The Best 20-Gallon Fish Tanks Available for Purchase

Let us now take a look at some of the most popular 20-gallon fish tanks available in the market and understand their pros and cons.


Tetra 20-Gallon Aquarium Kit

One of the most durable 20-gallon tanks available in the market, the Tetra 20-Gallon Aquarium Kit features a scratch-resistant glass that is extremely helpful, especially if you have young children at home.

The LED lighting system installed in the hood maintains a natural lighting ambiance inside the tank, which makes your aquatic pets feel at home. You also don’t have to worry about your aquatic pets and plants freezing to death since it features an efficient water heater.

The three-stage filtration system that comes along with this product helps in keeping the tank water aerated, healthy, odorless, and clean. However, we do think that the filter is a bit small for the tank. Not to forget, it is a whisper filter, meaning you can say goodbye to all those unnecessary noises generated by an ordinary filter. You will also get a Tetra Mini UL Heater with this product.

To mimic the natural habitat of your pet, it also comes with four artificial plants and an artificial Boxwood plant mat. It also gives you a lifetime warranty.

What We Like

  • Lifetime warranty.
  • Quiet filtration system.
  • Natural lighting system.
  • Scratch-resistant glass.
  • An efficient water heater.

What We Don’t Like

  • The filter is a bit small compared to the requirement of a 20-gallon tank.

Aqueon LED Aquarium Kit 20H Black

Next up on our list of the best 20-gallon fish tanks is the Aqueon Ascent LED Frameless Aquarium Kit 20 Gallon, which is rectangular in shape and is made of glass. As such, you don’t have to worry about the interior clouds becoming cloudy over time due to water exposure.

It features a user-friendly canopy on its hood which makes feeding of the aquatic pet very convenient. It also brings with itself a five-stage filtration system to make sure the tank water remains toxic-free 24×7. The filter also prohibits discoloration of the water and even removes odor. The bio-holster element present in the filter ensures there’s no ammonia and nitrates in the tank.

The canopy also has LED lights attached to it which ensures your tank stays illuminated for better visibility.

To help you set it up easily, the manufacturer has included a detailed instruction guide. Besides, you will also get a water heater, a thermometer, a water conditioner, a fish net, and premium fish food with it.

What We Like

  • Five-stage filtration system.
  • LED indicator serves as a reminder for when to change cartridges of the filters.
  • Includes heater and thermometer.
  • It comes with the starting supply of fish food.
  • Includes a fish net to handle the fish safely.

What We Don’t Like

  • Absence of hinge on the LED hood.

SeaClear Acrylic Aquarium

Available in both rectangular and hexagonal shape, the SeaClear Acrylic Aquarium is an acrylic aquarium, which is pretty convenient since it is easier to move around and handle. It also makes it more resistant to scratches and is ideal fortog families that have young children and pet dogs and cats.

It features a 15” (38 cm) light fixture and a reflector. Its lid is also quite firm. However, it doesn’t provide any other equipment. Depending upon how you see it, it can be both a boon and a disadvantage. You can see it as a way to make it more personalized by picking up the best equipment from the market instead of the one that a company generally provides. But for those who are pretty new to fishkeeping, buying the equipment can be taxing.

An underlying aspect of this tank is that it features rounded corners, which adds to its safety and style quotient. Based on our experience, we didn’t see any hard watermarks on its surface, which is always a plus point.

What We Like

  • Firm movable lid.
  • Lightweight.
  • Rounded corners.
  • Light fixture included.

What We Don’t Like

  • Its base could’ve been a bit stronger

Marina LED Aquarium Kit

In spite of having a traditional design, the Marina LED Aquarium Kit adds a style quotient to the room that you keep it in. Its jet black seams speak a lot about how sometimes a simple, subtle design is what one needs to decorate their living room. Its comparatively small stature is another saving grace, especially for those who are looking for a 20-gallon fish tank despite not having a large space to host it.

Among its many features, the one that really stands out is its highly-efficient heater, which is extremely reliable. It also features LED lighting that is neither too glaring nor too dim. Also, the light won’t burn a hole in your pocket since it is an energy-efficient light.

Speaking of the filtration system, it comes with the Marina Slim S20 clip-on filter. In addition, you will also get quick-change filter cartridges with it.  

The perks don’t end there since you will get a bottle of Fluval Max Fish Food as an initial supply of food for your fish and a bottle of Fluval Aqua Plus Water Conditioner to keep the tank water healthy. In addition, the manufacturers have also included a biological supplement in the kit that will help in nurturing beneficial bacteria in your tank.  

For easy access in setting up the tank, you will find a care guide in the product. The fish net that comes with this tank will help you in handling your aquatic pet delicately.

What We Like

  • User-friendly set-up alongside guide book.
  • Includes fish food, fish net, and water conditioner.
  • Additional filter cartridges.
  • Highly-efficient heater.

What We Don’t Like

  • Loud filter.
  • LED lights not sufficient to promote the growth of aquatic plants.

Glofish 20-Gallon Aquarium Fish Tank Kit

If we speak strictly on appearance, the Glofish 20-Gallon Aquarium Fish Tank Kit is probably the most magnificent tank on our list. With an out-and-out black background and black seams, it symbolizes what is Glofish best known for – highlighting your colorful aquatic pets.

Made of glass, it features an LED light in its hood. Instead of the traditional white light, it gives you a blue LED light, which adds a sense of vibrancy in your tank.

You will also get a Tetra Whisper 20 filter with this tank that will keep the tank water clean and healthy without producing any unnecessary noise. In addition, to maintain an optimal level of temperature inside the tank, the manufacturers of this product have included the Tetra Mini UL Heater.

To add to the color quotient even further, you will get three artificial Glofish brand plants and a yellow anemone which glows brightly under the tank light. They not only act as decorative elements, but also provide shelter and hiding spots to your aquatic pet.

To assist you further, they have included a set-up guide and samples of water conditioner and fish food in their kit. It also lets you choose from its wide range of colorful gravels to complete the look of your 20-gallon fish tank.

What We Like

  • Eccentric design alongside blue LED light and black background highlights the colorful fish.
  • Noiseless filter.
  • Set-up guide included.
  • Samples of fish food and water conditioner provided.
  • Water heater.

What We Don’t Like

  • Not suitable for black or dark fish since they won’t be properly visible in the black background.
  • Anemone can tear up easily.

Aqueon Ascent LED Frameless Aquarium Kit 20 Gallon

Next up, we have another Aqueon product on our list of the best 20-gallon fish tanks. We are talking about the Aqueon Ascent LED Frameless Aquarium Kit 20 Gallon that features the QuietFlow Power Filtration to clean your tank without all those loud noises, thereby assuring comfort for both you and your aquatic pets.

To help you go through the first few weeks, the product comes with the first filter cartridge. It also features an LED light that is attached to its cover. Through its switch, you can conveniently control when to switch on and off the lights, thereby ensuring proper rest period for your fish.  

Since it has a slated design, it appears that the tank is full; however, there will be a room of air at the back of the tank. But, if you are hosting those fish that are known for making leaps from the water surface, feel free to keep the water level a bit low so that they don’t hit the roof while leaping from the water surface.

Furthermore, you will also get a set-guide, fish food, and water conditioner, all included in the kit to make the initial few days of your fishkeeping experience smooth. Maintaining this tank is also very easy since you can easily clean the filter.

What We Like

  • Noiseless filtration along with first filter cartridge.
  • Easy to maintain and clean.
  • Comes with a set-up guide.
  • Fish food and water conditioner included.

What We Don’t Like

  • Quality of light could have been better.

Marineland AML11536 Glass Half Moon Shaped Aquarium

One of the most interesting-looking 20-gallon fish tanks available in the market, the Marineland AML11536 Glass Half Moon Shaped Aquarium will definitely be a head-turner. As the name suggests, it is shaped like a half-moon which gives a 180° seamless dynamic view of your aquatic pets and plants.

It comes with an in-built LED lighting system with 42 white LEDs and three blue LEDs powered by a low voltage adapter, which means that it is energy efficient by nature. The lights are perhaps the biggest selling point of this product, bringing with them a shimmering effect. Not only will they mimic the sunlight underwater, but they’ll also create a natural night-light to help your aquatic pet feel at home.

The canopy has a hole in it which makes feeding the fish extremely easy. It has been designed in a way that enables easy mounting of the filter. The canopies also help in less evaporation of tank water. The plastic-built of the tank makes it very durable.

The absence of a filtration system is disappointing, but if you can manage to buy that separately, this is actually a worthy buy.

What We Like

  • Unconventional 180° seamless dynamic view.
  • Extensive LED lighting system with 42 white LEDs and three blue LEDs.
  • Easy access to fish-feeding.

What We Don’t Like

  • Absence of a filtration system.


Many novice aquarists start their fishkeeping experience with a 20-gallon fish tank. As a result, they aren’t aware of how to handle them. Some don’t even know the key aspects regarding the functionalities of these tanks.  It is very important to go through reviews and make a wise judgment before buying the final product. We certainly hope that with our review of these aforementioned tanks, you now can evaluate their pros and cons in a better manner than before. So, choose wisely, and enjoy fishkeeping.

Similar Fishkeeping Guides

If you are looking for a different-sized tank, then these might interest you: