Best 20 Gallon Aquariums – Reviews And Buyer’s Guide

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A 20-gallon fish tank is the perfect starter aquarium for anyone wanting to begin their fish-keeping journey.

That size of aquarium is large enough to accommodate a nice community of different compatible fish species, invertebrates, and living plants without taking up too much space in your home. There are plenty of 20-gallon tanks to choose from, so where do you start?

Well, we’ve already done the hard work for you! 

Read this guide for reviews of the best 20-gallon aquariums on the market today.

Quick Comparisons Of The Best 20-Gallon Aquariums

IMAGE

BRAND


Tetra ColorFusion Aquarium

DETAILS

  • Perfect kit for a beginner
  • Includes a heater
  • Excellent quality

Pricing

BRAND


SeaClear Acrylic Aquarium Combo Set

DETAILS

  • Different shapes available
  • Lightweight acrylic material
  • Excellent quality

BRAND


Marina LED Aquarium Kit

DETAILS

  • Comes as a complete kit
  • Excellent quality glass tank
  • Suitable for saltwater and freshwater

BRAND


Landen 60P 17.1-gallon Aquarium

DETAILS

  • Completely customizable setup
  • Excellent quality glass tank
  • Suitable for saltwater and freshwater

BRAND


Aqueon Standard Glass Aquarium Tank 20 Gallon High

DETAILS

  • Customizable setup
  • Excellent quality glass aquarium
  • Suitable for saltwater and freshwater fish
Life 15 Aquarium with LED Light - 4 Gallon, Black

BRAND


Life 15 Aquarium with LED Light

DETAILS

  • Perfect mood lighting
  • Extremely attractive setup
  • Comes as a complete kit
Aqueon LED Aquarium Kit 20

BRAND


Aqueon LED Aquarium Kit 20 Gallon High

DETAILS

  • Low-profile LED hood
  • Energy efficient lighting unit
  • High-quality components

Why 20-gallon Fish Tank Kits Are Perfect For Getting Started

Although most newbies to the hobby start off with a 10-gallon tank, a 20-gallon aquarium kit is actually a much better choice.

For a start, aquarium kits come with all the equipment you’ll need to get started, so you don’t have the dilemma of what lighting, filter, heater, etc., to choose. Also, a larger tank is easier to keep safe for your fish since the water chemistry tends to be more stable.

Also, 20-gallon tanks are ideal for use as spawning or quarantine tanks and can be adapted for use as a hospital tank, too. 

Generally, 20-gallon aquariums are cube-shaped or rectangular, and they come in glass or acrylic. 

I recommend that you start with a rectangular tank. That shape offers a much better surface area for gaseous exchange, as well as providing plenty of swimming space for schooling fish and bottom-dwelling species. There’s also more room for plants and decorations.

How Many Fish Can You Keep In A 20-Gallon Tank? 

The general rule of thumb for stocking any fish tank is one inch of fish per gallon of water. So, in theory, you can have 20 inches of fish in your aquarium. 

However, that simple equation depends on several factors, such as the fish species and their behavior and the amount of waste produced by the fish. Large, territorial fish need more space than peaceful nano species, and very messy fish need more water to dilute the waste they produce.

What Fish Are Best For A 20-Gallon Tank?

A 20-gallon aquarium gives you plenty of scope when it comes to choosing what fish you’d like to keep. But before you rush to your local fish store or shop online, you need to do some research.

Size Matters!

When you’re choosing fish for your 20-gallon aquarium, be sure to check their adult size.

Most of the fish you see for sale in fish stores are juveniles that have a lot of growing to do. For example, a couple of months back, I bought two tiny fantail goldfish, measuring about 1 inch in length. Those same tiddlers are now approaching 3 inches long and will reach around 6 to 8 inches when fully grown!

Don’t overstock your tank. Too many fish leads to too much waste for your filtration system to cope with and poor water quality. Poor water quality stresses the fish and eventually causes outbreaks of disease. So, never try to cram too many fish into your tank.

Are The Fish Compatible?

School of fish in an aquarium

Your fish tank will not be a pleasure to keep if its inhabitants are always fighting! So, you need to pick a selection of fish that will get along.

When you first start off, it’s best to avoid highly territorial or semi-aggressive fish, such as bettas or some of the barb species. Also, fin nippers are best left out of the community. Finally, although tiny invertebrates, such as shrimp, can be a valuable and attractive addition to the tank as a cleaning crew, be aware that these tiny critters might also be regarded as an easy meal by large, predatory fish.

Environment

Ideally, the fish in your community will share the same basic requirements in terms of water parameters, including:

  • Temperature
  • pH
  • Hardness

The closer the water parameters in the tank to the fish’s natural habitat, the happier and healthier the fish will be. Most popular aquarium pet fish prefer neutral or soft water with a temperature of between 72° and 80°F. Some species can tolerate brackish conditions, whereas any salinity in the water would kill others.

So, be sure to carry out thorough research into the fish species that you want to keep together to make sure that they need the same conditions.

Diet And Nutrition

Boy feeding fish in the aquarium

Some fish are carnivores, some are herbivores, and others are omnivores. Picking fish that share the same feeding preferences makes catering for your pets much more straightforward and cheaper than trying to accommodate lots of different feeding requirements.

Also, if you include creatures, such as snails and shrimp, they will act as a cleanup crew, keeping the aquarium tidy by eating leftover fish food, algae, and general detritus.

Habitat

As well as diet and water parameters, it’s helpful if the fish you choose all share the same basic habitat preferences.

Schooling species need plenty of open water swimming space, whereas shy fish require dense planting and places to hide when they need to,  and others need a soft, sandy substrate that they can burrow into.

Providing the correct conditions for your fish is essential if they are to remain stress-free and healthy. 

Living Space

Aquascaping of the beautiful planted tropical freshwater aquarium

Different species swim in different parts of the water column.

For example, schooling species tend to swim in the middle of the water column, whereas catfish mostly hang out on the bottom of the tank. Labyrinth breathers, such as bettas and gouramis, like to stay relatively close to the water surface so that they can breathe atmospheric air when they need to.

So, by choosing fish that swim in different parts of the tank, you can avoid potential confrontations and make sure that everyone has plenty of room to do their thing without being overcrowded.

Fish For A 20-Gallon Aquarium

Here are some suggestions for the best fish for your new 20-gallon tank.

Nano Fishes

Many nano fish species are excellent for a community setup, being peaceful and tolerant of others in the tank. The following beginner-friendly fish are happiest when kept in groups or small schools, making a bright, colorful display.

Small Community Fish Species

These small fish generally mix well with other peaceful types and can make an attractive feature in your 20-gallon tank.

That’s only a very small selection of dozens of species that do very well in a 20-gallon aquarium. Don’t forget invertebrates, such as shrimp, snails, and even species of dwarf amphibians.

Can You Keep Live Plants in a 20-Gallon Aquarium?

Yes! 

Live plants are an excellent addition to any size of fish tank, and a 20-gallon setup gives you plenty of space to include a selection of plants. There are lots of plants that are perfect for beginners, being easy to grow and needing minimal care.

Top 7 20-Gallon Aquariums Review

Now, here’s our guide to seven of the best 20-gallon tanks that you might want to consider buying.

1. Tetra ColorFusion Aquarium

Tetra ColorFusion Aquarium 20 Gallon Fish Tank Kit, Includes LED Lighting and Decor
  • Perfect kit for a beginner
  • Includes a heater
  • Excellent quality

Tetra is a very well-established manufacturer of fish tanks and associated accessories, including heaters, filters, and even fish foods. 

This high-quality glass tank is perfect for a beginner because it comes complete with a lid, LED lighting unit, a heater, and a filtration system. You even get a selection of silk plants, which is great if you don’t want to care for living plants until you have more experience. All you need to add to the setup is some substrate, decorations, and fish.

The aquarium has a lifetime warranty for your peace of mind. Also, you get a bottle of water conditioner, a fishnet, and a few Tetramine sachets to start you off.

The rectangular tank measures 24.2 x 12.4 x 16.7 inches.

PROS

  • Includes everything you need for a tropical tank setup
  • Comes with a lifetime warranty
  • Extremely high quality

CONS

  • LED lighting unit bulbs are not very bright
  • Silk plants are not of good quality

2. SeaClear Acrylic Aquarium Combo Set

SeaClear Acrylic Aquarium Combo Set
  • Different shapes available
  • Lightweight acrylic material
  • Excellent quality

The SeaClear 20-gallon aquarium is an excellent choice if you have children and pets and you’re concerned about the safety aspect of having a glass tank in your home.

The beauty of this 20-gallon fish tank kit is that it’s available in different shapes and sizes, including rectangular and hexagonal styles. The tank comes with a 15-inch lighting unit and reflector so that you can customize the lights to fit your tank setup and plants.

From personal experience, I recommend the rectangular version of the tank, as that shape is easier to keep clean and to stock than a hexagonal one. The tank measures 24 x 13 x 16 inches.

PROS

  • Acrylic is lighter, stronger, and safer than glass
  • Tank is designed with rounded corners for safety
  • Extremely good clarity

CONS

  • The tank top is completely enclosed, making cleaning difficult
  • The plastic lid is rather flimsy

3. Marina LED Aquarium Kit

Marina LED Aquarium Kit
  • Comes as a complete kit
  • Excellent quality glass tank
  • Suitable for saltwater and freshwater

This beautiful glass fish tank comes with an excellent quality Marine Slim S20 HOB filter system, replacement cartridges, and an LED lighting unit. You also get a few handy extras, such as a water conditioner, supplements, and fish food samples. 

All you need to buy to go with the kit are water testing kits, living plants if you want to keep them, a heater if you’re keeping tropical species and your fish.

The rectangular glass tank measures the standard 24 x 12.5 x 16.5 inches and is suitable for both freshwater and saltwater species.

PROS

  • Excellent quality aquarium and accessories
  • Includes a helpful book on tropical fish care
  • Replacement filter cartridges included

CONS

  • The kit does not include a heater, which you’ll need to buy separately

4. Landen 60P 17.1-gallon Aquarium

LANDEN 1.6Gallon Rimless Low Iron Freshwater Fish Tank,10.63" L×10.63" W×4.72" H (27cmx27cmx12cm) 5mm Thickness, Glass Air Suspension Aquarium Multi-Scene Landscape Aquarium113001
  • Completely customizable setup
  • Excellent quality glass tank
  • Suitable for saltwater and freshwater

More experienced aquarists might prefer to buy a completely blank canvas that they can customize to suit their precise requirements. The Landon is inexpensive and allows you to completely customize your setup from the get-go rather than having to switch or replace equipment that you get with a starter kit.

The tank includes a black foam leveling mat and is made from 6mm thick low-iron glass, which offers superb clarity. The precisely applied silicone sealant is secure and leak-proof.

This rectangular aquarium measures 23.6 x 11.8 x 14.2 inches.

PROS

  • Excellent quality aquarium
  • Superior clarity for an excellent view of your fish
  • Completely customizable

CONS

  • You need to buy peripheral equipment separately

5. Aqueon Standard Glass Aquarium Tank 20 Gallon High

Aqueon Standard Glass Aquarium Tank 20 Gallon High
  • Customizable setup
  • Excellent quality glass aquarium
  • Suitable for saltwater and freshwater fish

Aqueon manufactures excellent quality products for the hobby, and this 20-gallon standard glass tank without equipment is ideal for you if you want to go the DIY route and customize your aquarium.

This rectangular aquarium measures 25 x 17.25 x 13.25 inches, making it the perfect size to create your perfect tank at a very affordable price.

PROS

  • Excellent quality aquarium
  • Very affordable
  • Completely customizable

CONS

  • You need to buy a heater, filter, and other equipment separately

6. Life 15 Aquarium with LED Light

Life 15 Aquarium with LED Light - 4 Gallon, Black
  • Perfect mood lighting
  • Extremely attractive setup
  • Comes as a complete kit

For something a little bit different, the Life 15 Aquarium is an attractively designed biOrb tank that’s shaped like a portrait. You can choose from transparent, white, or black trim so that the tank coordinates perfectly with your interior decoration scheme.

The main attraction of this tank is the remote-controlled lighting system. There are 16 pre-set colors to choose from, as well as a night/day setting. Thanks to the cleverly designed filtration system, you only need to carry out a 30% water change every four weeks.

PROS

  • Excellent remote-controlled lighting system
  • Concealed filtration system with minimal maintenance requirements
  • Beautifully designed

CONS

  • The tank doesn’t come with a heater

7. Aqueon LED Aquarium Kit 20 Gallon High

Aqueon LED Aquarium Kit 20
  • Low-profile LED hood
  • Energy efficient lighting unit
  • High-quality components

The Aqueon LED Aquarium kit has a sleek, low-profile LED hood with cool white modules that provide excellent illumination.

As you would expect from Aqueon, this tank comes with high-quality components, including a power filter, spare cartridge, and heater. You also get a thermometer, some fish food, a water conditioner, and a complete setup guide to get you started.

PROS

  • Energy-efficient lighting system
  • Comes complete with everything you need to get started
  • Sleek design

CONS

  • Power filter isn’t strong enough to cope with very messy fish, such as goldfish

In Conclusion

Did you enjoy our guide to the seven best 20-gallon fish tanks on the market today? If you did, please share.

A 20-gallon fish tank is an excellent size aquarium for a beginner. This size of tank doesn’t take up too much space and offers you the scope to keep a nice variety of community fish and plants.

What size fish tank do you have? Did you buy a complete kit or take the DIY route and customize your own?

Tell us in the comments box below!

Alison Page has been an avid fish keeper for over 35 years and has owned many different species of freshwater tropical fish including bettas. Currently Alison has two large freshwater tanks. The first tank has two huge fancy goldfish who are almost ten years old and still looking as good as ever. In the other, she has a happy community of tiger barbs, green tiger barbs, corydoras catfish, platys, and mollies.

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