Best 20-Gallon Fish Tank (Top 5 Reviewed)

A 20-gallon fish tank is a great option for those looking to add some aquatic life to their home. It is large enough to house multiple fish, but not so large that it is difficult to maintain. There are many types of fish that can thrive in a 20-gallon tank, making it a great option for both beginners and experienced fish keepers.

In this article, I’ll discuss the best 20-gallon fish tanks on the market, as well as a beginner’s guide on how to set up your aquarium.

Step-By-Step Guide for Setting Up a 20-Gallon Aquarium

Decorating a fish tank can be a fun and rewarding experience. Here are five tips to help you get started:

  1. Get the right tank size for your space. A 20-gallon aquarium is a great option for small apartments or homes.
  2. Choose the right location for your aquarium. It should be in a quiet room away from direct sunlight or drafts. Make sure your stand is sturdy and stable. Use a level to ensure the tank is level from front to back and side to side.
  3. Decide what type of fish you’d like to keep. Some fish require more space than others, so it’s important to choose fish that will be comfortable in a 20-gallon tank.
  4. Set up your filtration system and heating element before adding any water or fish to your tank. This will help ensure that your water is clean and the temperature is stable before adding fish.
  5. Add rocks, plants, and other decorations to your aquarium. Be sure to clean all items thoroughly before adding them to the tank.
  6. Place your aquarium on the stand or table and fill it with water. Use a water conditioner to remove chlorine and other impurities.
  7. Once your tank is set up, it’s time to add your fish.
  8. Choose low-maintenance fish species. Some good options include goldfish, bettas, and guppies.
  9. Don’t overcrowd your tank. A good rule of thumb is 1 inch of fish per gallon of water. So, for a 20-gallon aquarium, you should have no more than 20 inches of fish.

Best 20-Gallon Fish Tanks

#1. Best Overall: Tetra 20-Gallon Fish Tank

Tetra Aquarium 20 Gallon Fish Tank Kit, Includes LED Lighting and Decor
  • Tetra Glass Aquariums are made in the USA and are built to last with scratch resistant glass
  • The Tetra Aquarium comes loaded with an LED hood, that provides a natural daytime effect and a Whisper Filter that is whisper quiet while providing powerful, dependable water flow
  • Artificial Plants add a unique, natural ocean feel while giving your fish a place to hide which reduces fish stress
  • The Tetra Kit includes: one 20 Gallon Glass Aquarium, one LED hood, one Tetra Mini UL Heater, one Tetra Whisper 20 Filter, one artificial Boxwood Plant Mat, four artificial plants. Add gravel and fish to complete your aquarium
  • Aquarium Dimensions: 24.2" L x 12.4" W x 16.7" H
  • Material: Glass
  • Shape: Rectangular
  • Weight: 34.4 Pounds
  • Dimensions: 27.88″L x 16.13″W x 20.38″H

Made in the USA with scratch-resistant glass, the Tetra Aquarium 20-Gallon fish tank is the best choice for fish enthusiasts of all levels. The tank comes complete with a filter and air pump, making it easy to set up and maintain.

In addition to providing a natural daytime effect for your fish, the LED hood on the Tetra Aquarium also brightens up your fishing experience. 

It features a whisper-quiet filter that ensures dependable water flow. This is a great benefit to maintaining a healthy environment for your fish.

The tank also comes equipped with artificial plants and a Tetra mini UL heater, making it the ideal environment for your fish.

This complete set is perfect for anyone looking to add a touch of nature to their home or office.


  • Durable scratch-resistant glass
  • Whisper-quiet filtration
  • Comes with four artificial plants
  • Made in the USA


  • The LED hood is not high-quality

#2. Best Starter Kit: Aqueon 20-Gallon Aquarium

Aqueon Aquarium Fish Tank Starter Kit with LED Lighting 20 Gallon High Fish Tank
  • All the equipment needed to get started in one box
  • Kit includes: glass aquarium, low profile LED hood, QuietFlow power filter, filter cartridge, submersible preset heater, premium fish food sample, water conditioner sample, fish net, thermometer and setup guide
  • Preset heater will keep your aquarium temperature at a constant 78 degrees, appropriate for most tropical fish
  • Low profile full hood contains vibrant cool white LED lighting to bring your aquatic environment to life
  • Filter has a red LED light that flashes to indicate when it’s time to change the cartridge
  • Material: Glass
  • Shape: Rectangular
  • Weight: 33 Pounds
  • Dimensions: 24.25″L x 12.5″W x 19.5″H

This 20-gallon fish tank is perfect for fish enthusiasts who want to start small but still have a spacious and bright home for their finned friends. The best starter kit includes all the equipment you need to get set up and take care of your fish.

Your fish will love their new home under the bright, low-profile LED hood. The sleek design of the glass aquarium complements any room without taking up too much space.

The QuietFlow power filter keeps the water clean and healthy, while the submersible preset heater maintains a comfortable temperature for your fish.

Changing the filter is an important part of keeping your fish healthy, and this tank makes it easy by telling you when it’s time. The red LED light flashes when the water quality isn’t up to par, so you can quickly change the cartridge and get your fish back to swimming in clean water.

It comes complete with a water conditioner sample and setup guide to help you get started on creating a custom environment for your new fish friends.


  • A complete fish habitat
  • Enhanced five-stage filtration
  • Cartridge change indicator
  • Made in the USA


  • The filter is not ideal for small fish

#3. Best with Neon Display: GloFish 20-Gallon Aquarium Kit

GloFish 20 Gallon Aquarium Kit with LED Lights, Decor Heater and Filter
  • The blue LED light completely transforms your aquarium
  • GloFish and fluorescent décor create a colorful, neon display
  • GloFish Glass Aquariums are made in the USA and are built to last with scratch resistant glass
  • The Tetra GloFish Kit includes: one 20 Gallon Glass Aquarium, one LED hood, one Tetra Mini UL Heater, one Tetra Whisper 20 Filter, one GloFish 13" LED Light Stick, three GloFish Plants, one GloFish Yellow Anemone. Add gravel and fish to complete your aquarium.
  • Aquarium Dimensions: 24. 2" L x 12. 4" W x 16. 7" H
  • Material: Glass
  • Shape: Rectangular
  • Weight: 34.39 Pounds
  • Dimensions: 27.88″L x 16.13″W x 20.38″H

The GloFish tank is perfect for anyone looking to add a splash of color to their home. The Neon Display blue LED light not only illuminates the tank but also makes the fish glow brightly in a range of colors. The fluorescent decor is colorful and fun, and it’s the perfect way to add some life to your home.

This fish tank is for the long haul. With scratch-resistant glass made in the USA, you can forget about flimsy materials that only last a few years.

The LED hood with a 13-inch light stick emits natural-looking light that is beneficial for plant growth, while the Tetra Whisper 20 Filter provides powerful filtration to keep your water clean and healthy.

The Tetra Mini UL Heater will keep your fish warm and comfortable all winter long. The three GloFish Plants add a splash of color and can help purify the water. And the GloFish Yellow Anemone is a beautiful addition to this tank, and it’s sure to make your fish happy.

The GloFish 20-gallon fish tank is perfect for anyone who wants to add a little personality to their home while providing their fish with quality care.


  • LED light-stick pops of brilliant colors
  • Comes with three glofish plants and one anemone
  • Durable scratch-resistant glass


  • You have to buy gravel separate

#4. Best Value: Marina 20-Gallon Aquarium Kit

Marina Aquarium Kit - 20 gallon Fish Tank - LED
  • 20 U.S. gallon glass aquarium
  • Includes a Marina Slim S20 clip on filter with quick change filter cartridges
  • Includes everything you need to get your aquatic home started
  • Measures: 24 inches L x 12.5 inches W x 16.5 inches H
  • Material: Glass
  • Shape: Rectangular
  • Weight: 35 Pounds
  • Dimensions: 24″L x 12.5″W x 16.5″H

This sleek and chic fish tank is the best value for money. The polished-edged glass provides a clean, finished look that elevates the tank and its inhabitants – giving you a Crisp, ClearView of your lush underwater world.

The integrated LEDs in a low-profile canopy provide bright lighting. The rear cut-out makes it simple to install filters without having to remove the entire canopy.

This tank comes with a Slim S20 clip-on filter with quick-change filter cartridges that make replacing your filter a breeze. This will help you keep your tank clean and provide a healthy environment for your fish. This feature is perfect for those who want to have an easily accessible fish tank that doesn’t take up much space.

This aquarium kit is perfect for beginners. It includes a water conditioner and fish food, so you can get started right away. It also comes with a care guide to ensure that you’re providing the best possible care for your new fish friends.


  • Ideal aquarium kit for beginners
  • Includes water conditioner & biological supplements
  • Easy to assemble & change filter cartridge


  • The filter is a bit loud

#5. Best 360 View: Penn-Plax Bowl-Shaped Aquarium

Penn-Plax AquaSphere 360 Large Bowl-Shaped Aquarium for Freshwater and Saltwater Setups – Fully Integrated Filtration System and LED Light Display - Durable Polycarbonate – 24 Gallons
  • AWARD WINNING: We’re proud to announce that our AquaSphere 360 Aquariums were awarded as the winners of the 2019 Global Pet Expo New Product Showcase. In addition to their sleek and modern design, these bowl shaped tanks are constructed from scratch resistant polycarbonate. They’re great for keeping fish, crustaceans, and isopods!
  • LOOK MA, NO HANDS: Liven things up with an array of low voltage LED lights. Each AquaSphere 360 Aquarium features 13 LED bulbs hidden inside the black lid. The 13 bulbs consist of 1 White and 12 Blue. There’s no need to worry about losing another remote; the built-in motion sensors allow you to alternate light settings with a wave of the hand.
  • MORE THAN JUST A FISHBOWL: Along with the LED Lighting, our AquaSphere 360 Aquariums also feature an integrated filtration system connected through the top lid, complete with a submersible water pump and detachable protein skimmer (for saltwater / marine setups). Although each unit comes with a Bio-Sponge, the top lid contains 2 customizable media trays for aquarium filtration.
  • DON’T LET YOUR EYES DECEIVE YOU: No picture can do these AquaSphere 360 Aquariums justice, which includes capturing their size. Unlike traditional fishbowls, these tanks are rather large. The 24 Gallon Model (AS362) measures at 23.6” (Dia) x 17.9" (H). Furthermore, they’re made of strong, durable polycarbonate, and are viewable from every angle.
  • AVAILABLE IN 3 SIZES: Our AquaSphere 360 Aquariums are available in 3 sizes: 10 Gallon Capacity = 17.7” (Dia) x 14.4” (H), 14 Gallon Capacity = 19.7” (Dia) x 15.6” (H), and 24 Gallon Capacity = 23.6” (Dia) x 17.9" (H).
  • Material: Polycarbonate
  • Shape: Round
  • Weight: 16.7 Pounds
  • Dimensions: 23.6” (Dia) x 17.9″ (Height)

This fish bowl is the perfect way to view your aquatic friends from every angle. The unique design was awarded the Best 360 fish tank at the 2019 Global Pet Expo. Whether you have a betta fish or a school of platies, this bowl is sure to give you and your guests a fun and interactive way to view your pets.

This modern, sleek aquarium is scratch-resistant, so you don’t have to worry about unsightly scratches marring the beautiful polycarbonate design. This material is also much more durable than glass, so you can rest assured that your investment will last.

It has 13 LED bulbs hidden inside the black lid. This provides a well-lit aquarium for your fish to swim and play in. The 1 white bulb and 12 blue LEDs create a natural-looking light for your fish. And the built-in motion sensors make it easy to adjust the lighting with a wave of the hand.


  • Award-winning design
  • Integrated LEDs and filtration system
  • Detachable protein skimmer
  • Made of durable & scratch-resistant polycarbonate


  • Filtration is not that impressive

What Are The Best Fish for a 20-Gallon Tank?

There are a variety of different fish that can be kept in a 20-gallon aquarium. Swordtails and platies are both good choices because they are relatively small and do not require a lot of space. Panda Corydoras are also a good choice because they are peaceful and do well with other fish species.

Some more good options include:

You can read my detailed guide on the best fish for a 20-gallon tank.

Frequently Asked Questions

What is the maximum fish size to keep in a 20-gallon tank?

The recommended size per fish that can be housed in a 20-gallon tank is 2-3 inches. So, for this size, you can easily keep 6-8 fish in a 20-gallon aquarium. This is based on the rule of thumb that you can accommodate one inch of fish per gallon of water. Therefore, a 20-gallon tank can hold up to 20 inches of fish.

How to maintain a 20-gallon fish tank?

Here are a few tips on how to maintain your 20-gallon aquarium:

  • Change the water regularly. This means every 1-2 weeks, you should remove about 15-20% of the water and replace it with fresh, clean water.
  • Clean the filter every month or as needed. Depending on the type of filter and the number of fish you have, you will need to clean/replace it every 1-4 weeks.
  • Prune your plants regularly. This will help them stay healthy and prevent algae from taking over.
  • Scrub the algae off of the glass and decorations. Algae can be harmful to fish if it builds up too much.
  • Vacuum the gravel. Use a gravel vacuum to clean the gravel and remove any debris.