20 Gallon Aquarium: Our High 5 Decisions

If you're looking to get into the hobby of fish farming, a 20 gallon tank might be the ideal starter aquarium for you. A 20 gallon aquarium is big enough to hold a decent amount of biodiversity while it's small enough to be easy to maintain. In addition to fish, you can also keep invertebrates, including African dwarf frogs, shrimp, and snails.

However, there are literally dozen of 20 gallon aquariums to choose from. So where do you start? In this article, we're reviewing five of the best 20-gallon aquariums currently on the market. We'll also explain how to choose a fish community for your new aquarium and give you some suggestions on what livestock you could keep in your first home aquarium.

Best 20 Gallon Aquariums

Here is our guide to the best 20 gallon aquariums you might want to buy.

1. Tetra ColorFusion Aquarium

The Tetra ColorFusion 20 Gallon Aquarium is an ideal choice for beginners as it comes as a complete kit. With the tank you get a hood that contains an integrated LED lighting unit, a filter system and a heater. The package also includes a selection of four silk plants. This is great for beginners who don't care about live plants and don't want to keep fish. All you need to buy in addition to the kit is a substrate of your choice, a selection of decorations, and your fish.

It's reassuring that the aquarium has a lifetime warranty. As an added bonus, you get a few other items including some tetramine bags, a bottle of water purifier, and a fishing net.

The aquarium measures 24.2 x 12.4 x 16.7 inches and is made of scratch-resistant glass.

What we like:

  • The kit contains everything you need for a tropical setup
  • Lifetime guarantee
  • Quiet filter operation

Room for improvement:

  • External thermometer not very accurate
  • Artificial plants are not very realistic
  • Tank hood is weak
  • LED lights are not very bright

2. SeaClear Acrylic Aquarium

sale SeaClear 20 Gallon Acrylic Aquarium Combo Set, 24 x 13 x 16 ", Black

  • Combo contains aquarium, reflector and electrical 15 "light
  • Acrylic aquariums are clearer than glass, 17 times stronger and only half as heavy!
  • More impact resistant and less prone to chipping or cracking than glass, making it safer around children and pets

The SeaClear acrylic aquarium is an excellent alternative to a traditional glass fish tank. Acrylic is lighter and more flexible than glass and is also stronger and less prone to damage. So if you have children and pets in your house, an acrylic container is probably the safest option for you.

This tank is available in different shapes and sizes. The 20 gallon version is available in both hexagonal and rectangular designs. This very well made tank has a 15 '' lighting unit and reflector so you can easily choose your own lighting equipment that suits the needs of your fish and plants.

The rectangular version of the aquarium measures 24 x 13 x 16 inches.

What we like:

  • Acrylic is stronger and lighter than glass
  • Clarity is much better than glass
  • The tank has rounded corners for safety reasons

Room for improvement:

  • Plastic hood is rather thin
  • The top is closed, which makes maintenance and cleaning cumbersome

3. Landon 60P 17.1 Gallon Aquarium

If you'd rather create a custom aquarium, Landon's offer is an affordable alternative to a kit. Buying a basic aquarium allows you to choose a heater, filter, lighting unit, and other equipment that you need instead of potentially having to replace the components included in the kit if you decide to upgrade your setup later.

The tank is made of 6mm thick low-iron glass for excellent clarity and is extremely well made with a secure and cleanly applied silicone rim. The aquarium comes with a black foam leveling mat and measures 23.6 x 11.8 x 14.2 inches.

What we like:

  • Freedom to customize your setup
  • Excellent workmanship
  • Excellent clarity

Room for improvement:

  • The tank does not contain any additional equipment

4. Coralife LED Biocube Aquarium

The Coralife LED Biocube Aquarium is an excellent quality starter kit that has some features not offered by other kits.

You can use the Coralife aquarium for a freshwater or saltwater tank. The most attractive feature that you won't get in other aquariums is the LED lighting unit with three settings: color enhancement, sparkling blue and bright white. Thanks to a 24-hour timer, you can set the device so that it simulates the natural daylight cycle. There is a 30-minute program for sunrise and sunset and a 60-minute setting for moonrise and moonlight.

The tank is equipped with an integrated filter system to keep the water clean and healthy for your fish. However, the kit does not include a heater. So you will have to buy one separately if you want to keep tropical fish.

The aquarium measures 15 x 16.8 x 17.5 inches and is made of sturdy acrylic.

What we like:

  • Fabulous lighting system
  • Nice new design offers more space in the tank
  • Integrated filter system
  • Space for a UV sterilizer and a protein skimmer in a rear compartment

Room for improvement:

  • The design makes it difficult to change and clean filter sponges
  • The indoor fan in the tank hood is quite loud
  • The lighting can be too bright for some fish and plant species

5. Life 15 aquarium with LED light

biOrb Life 60 aquarium with MCR – 16 gallons, black

  • Made from acrylic – 10 times stronger than glass, 50% lighter and 93% transparent. Effortless Setup – Everything you need to start your aquarium is included.
  • Real 5-stage filtration – biological, mechanical, chemical, water stabilization and oxygen enrichment.
  • LED lighting – Multi-colored remote-controlled LED lighting with 16 preset colors and brightness control.

If you are looking for a really pretty aquarium that can comfortably house a small group of nanofishes like Tetras, the Life 15 Aquarium is for you.

This aquarium is one of a series of biOrb aquariums that are stylishly designed and offer you something that is a little different from the normal aquarium shape. The 16 gallon tank has a portrait shape and can be bordered with black, white, or clear trimmings so you can customize the tank to match your interior design.

A super cool feature of the aquarium is the remote-controlled multi-color lighting system that allows you to choose from 16 preset colors or choose the day and night setting for a more natural look. You can even set the brightness you want for your lighting and have the colors fade in and out!

The filter system is hidden under the ceramic substrate that is part of the kit and forms the biological filter medium. Fish waste and debris are collected in a filter cartridge at the bottom of the tank. All you have to do to service the tank is change the filter cartridge every four weeks and do a 30% water change.

The tank measures 16.5 x 11 x 25 inches and is made of durable acrylic. To put your mind at ease, this aquarium comes with a two-year guarantee.

What we like:

  • Very attractive design with a concealed filter system
  • Excellent, versatile, remote-controlled lighting system
  • Two year guarantee

Room for improvement:

  • The filtration system is not powerful enough to deal with dirty fish species like goldfish
  • The kit does not include heating

Ideas for Stocking a 20 Gallon Tank

You have now selected your perfect aquarium. What types of fish can you keep? Here are some ideas for stocking up a 20 gallon aquarium. All of the fish we suggest are available from your local fish shop or online.

Do some research before you buy …

Before you buy a fish for your aquarium, you need to do some research first.


First of all, you need to make sure that the fish you choose get along well with each other. The last thing you want is for your new pets to start fighting and hurting each other!

Some species, like Bettas, look absolutely stunning with their flowing tails and bright colors, but the males are very territorial and do not get along with other semi-aggressive species. Also, species of fin nibblers such as tetras and barbs are most likely to pester a betta fish, potentially stressing it and making it sick.

Remember that very small fish and invertebrates such as shrimp can be considered a source of food by larger species.


Also, check the size of the fish you have chosen at the time of maturity. This cute little fantail goldfish may now only measure two inches, but did you know that it can reach a whopping six inches or more when fully grown?

The general rule of thumb for inventory levels is to allow for one inch of fish per gallon of water. However, fish species that produce a lot of waste or are particularly active or territorial need more space to be comfortable. Do not try to overfill your tank. Too many fish put a very strong bio-load on the filtration system, potentially leading to dirty water that will ultimately harm your pets.

Water parameters

So you've picked a few species that get along with each other and you know they won't grow out of the tank. Now you need to check that the fish you have chosen is happy in the same water conditions.

The right water temperature is critical if you want your fish to stay healthy and happy in their new home. Even cold water species can suffer from temperature shock if the water in their tank is too warm, and tropical fish are not one size fits all when it comes to temperature.

Water hardness and pH are also important factors to consider when choosing tankmates for a community setup. It's really about what conditions the fish are used to in their natural environment. Some fish can handle brackish water while that would kill others. Many fish require very soft or neutral water, but some prefer water with a higher mineral content. Do your research again before buying.


Some fish are omnivores, others are carnivores, and some are vegetarians. When you choose fish species that share the same nutritional needs, feeding your pets will be much easier and cheaper. Fussy feeders are also best avoided as they can be difficult to keep healthy.

Many fish like to graze on the algae, which sometimes grow in a tank. Adding shrimp and snails to your community will help keep the tank clean by living on algae and fish scraps that fall from above onto the substrate.

Preferred habitat

Another important consideration when choosing fish is whether the species you are considering share the same habitat preferences.

Some fish like lots of places to hide and rest, some need lots of open water to swim, some are happiest in an environment with dense vegetation and floating plants that provide hiding places and diffused bright light, and some like to dig and dig in a soft, sandy substrate. If you choose fish species that enjoy the same conditions, your community will be happy and harmonious. This is important because stressed fish can suffer from weakened immune systems, making them prone to disease and parasite attacks.

Swimming room

Finally, you should know that different types of fish like to swim in different areas of the tank.

For example, Corydoras catfish are bottom-dwelling fish that spend 95% of their time looking for scraps of food in the substrate and between plants. Betta fish, on the other hand, hang around in the upper areas of the water column and feed and take in air at the surface of the water. Gouramis and barbs spend their time in the middle of the water column, occasionally making excursions to the surface or to the bottom to forage for food.

So if you choose fish species that live in different areas of the tank, there will be enough space for them all and the risk of overcrowding will be reduced.

Nano fish

Small fish species are often referred to as nanofishes in the hobby. Nano-species are generally very peaceful and can be kept together safely. Here are some cute little species of fish that generally get along well, make a bright, colorful display, and are suitable for beginners.

Note that all of these species are school fish by nature and are best kept in groups of at least six species.

  • Guppies
  • Platies
  • Mollies
  • Swordtails
  • Neon tetras
  • Zebra danios
  • Harlequin Rasboras

Small fish

Here are a few more small species that get along well with most other fish and make attractive additions to a community tank.

  • Corydoras Catfish
  • Dwarf gouramis
  • Rosy barbs
  • Rainbow fish
  • Bristle catfish

This, of course, is only a small selection of the hundreds of species of fish that are suitable for life in a 20 gallon aquarium. Before making your choice, as described above, do plenty of research and don't be afraid to ask the knowledgeable staff at your local fish shop for further advice and guidance.

Final thoughts

If you are thinking of getting into the hobby of fish farming, or if you started with a standard nanotank and want to increase the size, a 20 gallon aquarium is the perfect choice for you.

20 gallon aquariums allow you to keep a nice variety of fish species without taking up too much space in your home. You can choose a type of kit setup that includes everything you need to get your tank working, or you might prefer to buy a standard tank and select all of the equipment you need separately for a fully customized aquarium.

Whatever your preference, you can find something to suit your needs in our product list. Simply order online to get started right away.

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