20-Gallon Fish Tank: Our Top 5 Choices

If you want to get into the fish keeping hobby, a 20-gallon tank could be the ideal size starter aquarium for you. A 20-gallon fish tank is big enough to accommodate a decent range of species while being small enough to maintain easily. As well as fish, you can keep invertebrates, too, including African Dwarf frogs, shrimp, and snails.

However, there are literally dozens of 20-gallon aquariums to choose from, so where do you start? In this article, we review five of the best 20-gallon fish tanks that are currently on the market. Also, we explain how to choose a community of fish for your new tank, and we provide you with a few suggestions on what livestock you could keep in your first home aquarium.

Best 20-gallon fish tanks

Here’s our guide to the best 20-gallon fish tanks that you may like to consider purchasing.

1. Tetra ColorFusion Aquarium

The Tetra ColorFusion 20-gallon aquarium is an ideal choice for a beginner as it comes as a complete kit. With the tank, you get a hood that includes an integrated LED lighting unit, a filter system, and a heater. The package also includes a selection of four silk plants, which is great for a novice who doesn’t want to take on caring for living plants, as well as keeping fish. All you need to buy in addition to the kit are some substrate of your choice, a selection of decorations, and your fish.

Reassuringly, the aquarium comes with a lifetime warranty. As an extra bonus, you get a few other items, including some tetramine sachets, a bottle of water conditioner, and a fish net.

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

What we like:

  • Kit includes everything you need for a tropical setup
  • Lifetime warranty
  • Quiet filter operation

Room for improvement:

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

2. SeaClear Acrylic Aquarium

SeaClear 20 gal Acrylic Aquarium Combo Set, 24 by 13 by 16″, Black

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

The SeaClear acrylic aquarium is a superb alternative to a traditional glass fish tank. Acrylic is lighter and more flexible than glass, and it’s also stronger and less prone to sustaining damage. So, if you have kids and pets in your home, an acrylic tank is probably the safest option for you.

This tank comes in several different shapes and sizes, and the 20-gallon version is available in both hexagonal and rectangular designs. This very well-made tank has a 15-inch lighting unit and a reflector, making it easy for you to choose your own lighting equipment to suit 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 of view is much better than glass
  • Tank has rounded corners for safety

Room for improvement:

  • Plastic hood is rather flimsy
  • Top is enclosed, making maintenance and cleaning awkward

3. Landon 60P 17.1-gallon Aquarium

If you prefer to create a custom fish tank, this offering from Landon makes a cheap alternative to a kit. If you buy a basic aquarium, you can choose a heater, filter, lighting unit, and any other equipment that you need, rather than potentially having to replace what’s included with a kit if you later decide to upgrade your setup.

The tank is made from 6mm thick low-iron glass for excellent clarity and is extremely well-made with secure and neatly applied silicone rimming. 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 quality workmanship
  • Superb clarity

Room for improvement:

  • Tank doesn’t include any additional equipment

4. Coralife LED Biocube Aquarium

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

You can use the Coralife aquarium for a freshwater or saltwater tank, but the most appealing feature that you don’t get with other aquariums is the LED lighting unit that has three settings: color enhancing, sparkling blue, and vibrant white. You can set the unit to replicate the natural daylight cycle thanks to a 24-hour timer. There are a 30-minute sunrise and sunset program and a 60-minute moonrise and moonlight setting too.

The tank comes with an integral filtration system to keep the water clean and healthy for your fish. However, the kit doesn’t include a heater, which means you’ll need 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 from sturdy acrylic.

What we like:

  • Fabulous lighting system
  • Nice new design provides more space inside the tank
  • Integral filter system
  • Has space for a UV sterilizer and protein skimmer in a rear compartment

Room for improvement:

  • The design makes it awkward to change and clean filter sponges
  • The interior fan in the tank hood is quite noisy
  • Lighting may be too bright for some species of fish and plants

5. Life 15 Aquarium with LED Light

biOrb Life 60 Aquarium with MCR – 16 Gallon, Black

  • Constructed Out of Acrylic – 10 times stronger than glass, 50% lighter and has a 93% transparency rating. Effortless Set Up – Everything you need to start your aquarium is included in the box.
  • True 5 Stage Filtration – Biological, Mechanical, Chemical, Water Stabilization and Oxygenation.
  • LED Lighting – Multi-Color Remote controlled LED lighting with sixteen preset colors and brightness control.

If you want a really pretty aquarium that can comfortably house a small group of nano fish, such as tetras, the Life 15 Aquarium could be perfect for you.

This fish tank is one of a series of aquariums made by biOrb that is designed to be stylish and offers you something that’s a little bit different from the regular aquarium shape. The 16-gallon tank is portrait-shaped and can be edged in black, white, or transparent trim, enabling you to match the tank to complement your interior home decorative scheme.

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

The filtration system is hidden beneath the ceramic substrate that comes as part of the kit and forms the biological filtration media. Fish waste and detritus are collected in a filter cartridge in the base of the tank. All you need to do to maintain the tank is to change the filter cartridge every four weeks and carry out a 30% water change.

The tank measures 16.5 x 11 x 25 inches and is made from durable acrylic. For peace of mind, you get a two-year warranty with this aquarium.

What we like:

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

Room for improvement:

  • Filter system is not powerful enough to cope with dirty fish species such as goldfish
  • Kit doesn’t include a heater

Ideas for stocking a 20-gallon tank

So, now you’ve chosen your perfect fish tank, what fish species can you keep? Here are a few ideas for stocking a 20-gallon aquarium. All the fish we’ve suggested are readily available from your local fish store or online.

Research before you buy …

Before you buy any fish for your tank, you must do some research first.


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

Some species, such as bettas, look absolutely stunning with their flowing tails and bright colors, but males are highly territorial, and they don’t get along with other semi-aggressive types. Also, fin nipping species, such as tetras and barbs, will most likely hassle a betta fish, potentially stressing him out and making him sick.

Bear in mind that very small fish and invertebrates, such as shrimp, could be regarded as a food source by larger species.


Also, be sure to check the size of your chosen fish at maturity. That cute little fantail goldfish might measure just two inches now, but did you know he could reach a whopping six inches or more when he’s full-grown?

The general rule of thumb for stocking levels is to allow one inch of fish per one gallon of water. However, fish species that produce a lot of waste or are especially active or territorial will need more space than that to be comfortable. Don’t be tempted to overstock your tank. Too many fish places a very heavy bioload on the filtration system, potentially leading to dirty water, which will ultimately harm your pets.

Water parameters

So, you’ve chosen some species that will get along, and you know that they won’t outgrow the tank. Now, you need to check that the fish you’ve chosen will be happy in the same water conditions.

The correct water temperature is crucial if your fishes are to remain healthy and happy in their new home. Even coldwater species can suffer from temperature shock if the water in their tank is too warm, and tropical fish don’t have a one-size-fits-all when it comes to temperature either.

Water hardness and pH are also vital factors to consider when choosing tankmates for a community setup. It’s really all about what conditions the fish are accustomed to in their natural environment. Some fish can cope with brackish water, whereas that would kill others. Many fish need very soft or neutral water, but some prefer water with higher mineral content. Again, do your research before you buy.


Some fish are omnivores, some are carnivorous, and a few are vegetarian. If you pick fish species that share the same dietary requirements, feeding your pets will be a whole lot easier and less expensive. Fussy feeders are best avoided, too, as they can be difficult to keep healthy.

Many fish enjoy grazing on the algae that sometimes grow in a tank. In fact, if you add shrimp and snails to your community, they will help to keep the tank tidy by living on algae and leftover fish food that drifts down onto the substrate from above.

Preferred habitat

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

Some fish like plenty of places to hide and rest, some need lots of open water for swimming, some are happiest in an environment with dense planting and floating plants that offer hiding places and diffuse bright lighting, and some like to burrow and dig in a soft, sandy substrate. If you choose fish species that enjoy the same conditions, your community will be happy and harmonious. That’s important, as stressed fish can suffer from a compromised immune system, which leaves them vulnerable to disease and attack by parasites.

Swimming space

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

For example, Corydoras catfish are bottom-dwelling fishes that spend 95% of their time foraging for scraps of food in the substrate and among plants. Betta fish, on the other hand, hang out in the upper regions of the water column, feeding and taking gulps of air at the water surface. Gouramis and barbs tend to spend their time swimming around in the middle of the water column, making occasional trips to the surface or to the bottom in search of food.

So, if you choose fish species that inhabit different areas of the tank, there will be plenty of space for everyone, and the risk of overcrowding is reduced.

Nano fish

Small species of fish are commonly referred to in the hobby as nano fish. Nano species are generally very peaceful and can safely be housed together. Here are some nice small fish species that generally get along well together, make a bright, colorful display, and are suitable for a beginner to care for.

Note that all these species are naturally schooling fish that do best when kept in groups of at least six.

  • 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 an attractive addition to a community tank.

  • Corydoras catfish
  • Dwarf gouramis
  • Rosy barbs
  • Rainbowfish
  • Bristlenose catfish

Of course, that’s just a small selection of the hundreds of fish species that are suitable for life in a 20-gallon fish tank. Before making your choice, do lots of research as outlined above, and don’t be afraid to ask for more advice and guidance from the knowledgeable staff in your local fish store.

Final thoughts

20 gallon freshwater small planted aquarium

If you’re thinking of getting into the fish keeping hobby, or you started with a standard nano tank, and you want to upsize, a 20-gallon fish tank is a perfect choice for you.

20-gallon aquariums enable you to keep a nice selection of fish species without taking up too much space in your home. You could choose a kit type of setup that includes everything that you need to get your tank up and running, or you may prefer to purchase a standard tank and separately choose all the equipment that you need so that you end up with a fully customized aquarium.

Whatever you prefer, you’ll find something suitable for your needs in our product list. Simply order online to get started right away.


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