20 Gallon Fish Tanks & Aquariums

Latest posts by Sam (see all)

If you’re a beginner and looking for an ideal tank to get started with fishkeeping, then a 20 gallon aquarium is probably one of the best sizes of tank you could go for. It’s big enough to be comfortable for most breeds of fish, but small enough to fit comfortably into most homes, and won’t take up much more room than a 10 gallon aquarium or even 5 gallon aquarium. So we decided to create a list of the best 20 gallon aquarium kits (because kits include everything you need to get started) that you can buy online right now. But before we get into the more detailed guide, here is a quick overview of the best tanks we’ve found at this size:

Best 20 gallon aquariumsSellerWhere to buy
Tetra kitAmazonCheck Price
Marina kitAmazonCheck Price
Aqueon kitAmazonCheck Price
Tetra Deluxe kitAmazonCheck Price


And now for the more detailed reviews:

Tetra ColorFusion Aquarium 20 Gallon Fish Tank Kit

This is a glass tank made in the USA by Tetra with a huge amount of positive reviews (over 260 of them), with many of the reviewers claiming that this is one of the best aquariums they’ve ever owned. High praise indeed, but when you take a closer look at this 20 gallon fish tank, it isn’t hard to see why people would getting excited about this Tetra tank. Part of the reason that people seem to love this fish tank so much is that it comes with a load of extras, including:

  • Made with scratch resistant glass LED hood – provides a natural daylight glow
  • Whisper filter – quiet yet effective filtering
  • UL Heater and a Tetra Whisper 20 Filter
  • Color Changing LED
  • Dimensions – 24.2″L x 12.4″W x 16.7″H
Aqueon Aquarium Fish Tank Kit, 20 gallon

Aqueon Aquarium Fish Tank Kit

Aqueon create brilliant aquariums, and this tank is no exception to that. The tank is made from glass and includes a low profile hood containing white LED lights. Because this is a kit, it includes everything you need to get started (so it’s great for beginners). The kit includes:

  • QuietFlow 10 LED PRO power filter with medium cartridge
  • 100W preset heater
  • Fish food
  • Water conditioner
  • Fish net
  • Stick-on thermometer

Tetra 20 Gallon Fish Tank (Hooded & less than $120)

This is probably the best aquarium in this list – not just because it looks awesome, but also because it’s very highly rated. It’s got an average score of 4.6 stars from over 20 reviews, which is very decent. Also, it’s reasonably priced for the fish tank. There are some other cool features to consider with this fish tank, including: Made from glass Available in black Rectangular shape Fluorescent hood lamp Center braced framing to prevent glass bowing Dimensions – 12.5 inches x 24.25 inches x 16.75 inches Feel free to check out the 10 gallon version of this fish tank

Marineland BioWheel LED Aquarium Kit

Kits are always a good idea for beginners, but they also can be great for anyone looking to get an ‘all in one’ solution for their fish. This Marineland 20 gallon aquarium kit is awesome because of all of the extras that it comes with. It’s also got a ton of positive reviews, with over 120 people purchasing this aquarium and reviewing it. This aquarium kit is actually available in 2 other sizes (29 and 55 gallons) but obviously we’re talking about the 20 gallon variety here! Other notable features of this tank include: Made from glass Penguin 150 BioWheel (keeps water pure) LED lighting system Easy access hood Submersible heater Thermometer Fish net & food Available in black Dimensions – 14.5 inches x 26 inches x 18.5 inches

Aqueon Hex 20 Gallon Fish Tank Starter Kit

Don’t be fooled by the fact that this is described as a ‘starter aquarium kit’ – that doesn’t necessarily mean it’s only suitable for beginner fish keepers. This fish tank should be considered as the ultimate 20 gallon aquarium in our opinion. Aside from looking cool and having a badass name (‘Hex’ sounds like a superhero name), it also comes with a load of super useful extras, including: LED hood – (designed to be low profile to prevent your fish from being disturbed) Power filtration Submersible heater Made from glass Fish net & food Thermometer Set-up guide Water conditioner

SeaClear Hexagon Tank

We actually featured this 20 gallon tank on the homepage of our site for a while because people loved it so much, but now we’ve included it in this list. The unique shape of this fish tank makes it perfect for any home where space is limited and needs to be used sparingly. But it’s not just the cool hexagon shape that makes this tank a firm favorite of ours – there are a few other features that we’re fans of, including: Made from acrylic – lighter and stronger than glass Suitable for freshwater and saltwater Leak resistant – rounded corners Fluorescent light fixture Dimensions – 20 inches x 28 inches x 18 inches

Marina LED 20 Gallon Fish Tank Kit

This is an extremely highly rated fish tank (an average score of 4 and a half stars from over 180 reviews!) which makes it an absolutely excellent choice for anyone who needs everything required to get started with their aquarium. Marina are an excellent company and this 20 gallon fish tank truly reflects that. If you scroll through the reviews then you’ll find several examples of people who really seemed to love this fish tank, and they’ve posted their own photos too. Other features of this aquarium include: Daylight effect LED lighting module Fish food and net Water conditioner Aquarium set up guide Dimensions – 26 inches x 15 inches x 19 inches

SeaClear Aquarium & Hood

This is a pretty straightforward 20 gallon aquarium from SeaClear. The most notable feature of this fish tank is that it is made from cast acrylic, which is generally considered to be one of the finest materials that your tank can be made from, giving you years of use from them. There are plenty of extras that you get with this aquarium, including: Suitable for freshwater and saltwater use Fluorescent hood Lifetime warranty against leakage Filtration system Available in Cobalt Blue color Dimensions – 13 inches x 24 inches x 16 inches


You could get a custom fish tank like this if you order from us.

Clear-For-Life Rectangular Aquarium

This is another pretty simple 20 gallon fish tank, again made with the highest quality acrylic. This essentially makes it stronger and lighter than most other aquariums out there. Other notable features of this tank include: Suitable for both freshwater and saltwater Rectangular shape Dimensions – 30 inches x 10 inches x 14 inches Available in blue, black or white

SeaClear Hexagon 20 Gallon Fish Tank Kit

We’ve already got a SeaClear 20 gallon hexagon aquarium in this list, but this is a full kit which is perfect for beginners as it includes just about everything you’d need to get started with fish keeping (if you don’t have it already). All of the accessories that come with this kit have been included because they’re all really useful. The kit includes: Fluorescent fixture Aquarium made from acrylic Fish net & food Plant decorations Water conditioner External power filter Dimensions – 20 inches x 28 inches x 18 inches

Elive Aqua Duo LED Aquarium Kit

Elive are a cool company that don’t have a huge amount of products available, but the ones that they do have are always popular. This Aqua Duo aquarium kit is no exception – complete with a cool haircut, this tank is an awesome choice that comes with a few handy extra features too, including: Filter Hidden LED lighting system Heater Set up guide included Dimensions – 25 inches x 14 inches x 17 inches

20 Gallon Fish Tank Stands

Aquatic Fundamentals 20 Gallon Aquarium Stand

We had to end our list with a stand, and this is such a sexy sexy stand (just look at those legs!). This is from Aquatic Fundamentals, who are stand specialists, and what we love about this stand is that it is designed specifically for 20 gallon tanks. It isn’t just all good looks though, this stand also includes: Moisture resistant coating Ready to assemble immediately Storage space Dimensions – 24 inches x 12 inches x 27 inches Weight – 13 pounds

A 20 gallon fish tank is a very popular size for most fish keepers – they’re a great ‘medium’ size of aquarium which won’t just keep most sizes of fish happy, they’ll also generally fit in most areas of your home (which is always handy if you don’t live in a mansion!). The tanks that we’ve included in this list have been included for 2 reasons – we’ve either got first hand experience of them, or they’ve been highly rated online. Hopefully you’ll find a 20 gallon aquarium that suits your needs!


The great thing about our selection of 20 gallon tanks is that it includes aquariums of all shapes and sizes. We’ve got long aquariums with longer dimensions, and we’ve got tanks which are slightly taller too. This includes the popular brand Aqueon, who are specialists in tanks of this size.


How many fish should be in a 20 gallon tank?

This will obviously depend on the breed and size of the fish, but we would recommend no more than an inch of fish per gallon of tank as a rough estimate.

How big are these tanks?

It’s important to remember that these tanks aren’t massive, so you should be considerate of how much your tanks can handle.

Are these suitable to use as reef tanks?

Absolutely, 20 gallons is more than enough to create a cool reef tank. You might not have as much room to create the kind of reef tank which will accurately mimic the natural habitat of a fish in the wild, but they’ll still be great on a much smaller scale.

How about saltwater and freshwater?

It’s perfectly fine for a 20 gal tank to be used as a saltwater or freshwater tank, however please ensure that you have carried out sufficient research on your fish so you know what their preferred environment is before implementing a water change.