best 20 gallon aquarium

Best 20 Gallon Aquarium | 2022 Reviews

Fish tanks offer visual entertainment for yourself and guests in your home, and they can be good conversation starters. Aquatic creatures make excellent pets because they require very little upkeep overall. They are colorful and can bring a room to life.

For first-time fish owners, it can be overwhelming to try and figure out which size of aquarium is best and what all you need to get started. If you are not sure if a 20 gallon tank will work for your plans, a good rule to follow is that your fish should have at least a gallon to swim in for every inch of length they are in size. This article will go over what you need to know to buy, set up, and maintain an aquarium.

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Best 20 Gallon Aquarium Reviews

There is a wide range of tanks to choose from, and they come with various features. Below are five of the best 20 gallon aquariums for new or experienced fish owners. Each product summary includes a complete list of all items that come with the product so you know what additional accessories you may need to purchase to complete your tank set up.

Tetra Aquarium 20 Gallon Fish Tank

best 20 gallon aquarium

Dimensions: 24.2″ L x 12.4″ W x 16.7″ H

Tetra is one of the most trusted brands, and this 20 gallon tank comes ready to set up with LED lights built into the top and some artificial boxwood to create a place for your fish to lurk and feel safe.

The glass is scratch-resistant, and this tank comes with both a Tetra HT 20 Heater and a digital thermometer, so you can easily keep it at an ideal temperature for whatever breed you stock. The Whisper Filter keeps the water circulating with a soft humming noise that easily fades into the background.

Four artificial plants are included to help create a natural ocean feel and giving your fish a place to hide or rest as needed.

The Tetra Aquarium is a good product for new or experienced fish owners. However, it does not have as many starter items as some other kits, so you may need to spend slightly more getting it ready for its new inhabitants. If you are not new to owning fish but are simply upgrading to a larger size, this is a fantastic option.

You will get a few additional accessories with this tank, including a 4-inch fish net, adapter, AquaSafe sachet, TetraMin sachet, 37-inch hinge frame top for easier access, and a printed-out walkthrough for setting up your new aquarium.

Aqueon Aquarium 20 Gallon Starter Kit

best 20 gallon aquarium

Dimensions: 24.25″ L x 12.5″ W x 19.5: H

Everything you need to start a healthy ecosystem is included with this tank, making it convenient for anyone who has never previously owned fish. This Aqueon aquarium comes with some helpful maintenance features, including the LED alert on the filter, which will turn red when you need to switch out the cartridge.

You can keep your fish healthy and thriving in this beautiful 20 gallon glass tank that features a helpful feeding door in the low-profile hood and LED lighting on the cover.

In this kit, you will find an Aqueon QuietFlow LED PRO filter, stick-on thermometer for the outside of the tank, set up walkthrough, fish net, water conditioner, fish food, heater, and LED lights in the hood.

GloFish Aquarium 20 Gallon Fish Tank

best 20 gallon aquarium

Dimensions: 24.2″ L x 12.5″ W x 16.2″ H

GloFish are genetically engineered fish with a special fluorescent glow that comes in red, blue, green, orange, purple, and pink. The GloFish Aquarium 20 gallon tank is specifically designed to enhance the unique appearance of GloFish by providing bright LED lights and colorful artificial plants to make the whole tank and your fish attention-grabbing. This is an eye-catching tank meant to house the various GloFish breeds, and it makes a fun first tank for any age.

Your patented GloFish tank includes a set of LED lights in the hood, Tetra Mini UL heater, Tetra Whisper 20 filter, GloFish 13″ LED light stick, three artificial GloFish plants, yellow anemone, fish food, water conditioner, and a printed guide for putting everything together.

Tetra ColorFusion Aquarium 20 Gallon Fish Tank

20 gallon aquarium

Dimensions: 27.88″L x 16.13″W x 20.38″H

The Tetra ColorFusion Aquarium is an excellent tank for brand new fish owners looking for something that will be entertaining to watch and a good conversation starter. 

The included decorations are colorful. When combined with the bright artificial plants, the whole tank stands out instead of fading into a room’s background. 

Glass Tetra aquariums are scratch-resistant, and they all have a lifetime warranty against product defects, making them a long-lasting, attractive investment.

Your Tetra ColorFusion kit will include a ColorFusion universal color-changing LED, Tetra Whisper 20 filter, Tetra UL heater, two Wonderland Plant multipacks, blooming white anemone, 4-inch fish net, digital thermometer, adapter, AquaSafe sachet, TetraMin sachet, and a convenient 37-inch hinge frame top for your tank.

Aqueon Aquarium 20 Gallon Fish Tank

20 gallon aquarium

Dimensions: 30.25″ L x 12.5″ W x 12.75″ H

If you are an experienced fish owner or are simply looking to upgrade your tank space so you can add a few more schools, then the Aqueon Aquarium 20 gallon fish tank is perfect. It does not include any of the frills, and you will need to have the filters, heaters, and other necessary equipment. The Aqueon is a beautiful tank and will easily fit many new aquatic pets.

Equipment Needed for Setup

Once you decide which tank will work best for your experience level and the type of aquarium you want to design, it is time to get the accessories. You will need these pieces of equipment to make your tank liveable and safe for any fish you purchase.


Any filter you have attached to your tank needs to be capable of handling around 80 gallons of water per hour or four times the volume of water present. The filter is responsible for removing debris, waste, and excess food. There several materials that can be used inside the filter cartridge include the following.

  • Filter floss for some older filters
  • Pads of sponge or foam are common
  • Combination cartridges have several different mediums inside

You have to regularly change out the cartridge or the internal media, depending on the kind you have. How often will depend on many factors, and you should follow the manufacturer guidelines that come with your specific filter. If you do not properly maintain your filter, it can cause the tank’s entire ecosystem to fail.


Maintaining a balanced temperature throughout the day and night is essential, and the heater will make sure the tank water does not get too cold. There are a couple of different kinds of heaters, and they include fully and partially submerged models.

The submersible heaters can provide more consistent heat throughout the tank, making them easier to deal with when cleaning the tank. You do not have to be concerned about forgetting to turn them off when removing some of the water because they stay under the waterline.

Regularly check your tank’s temperature because heaters can malfunction or break, leading to the water getting overheated or too cold. Heaters can last months or years, so you need to keep an eye on them to ensure your fish do not suffer from a sudden temperature change.


The temperature of your tank is vital for your fish’s health, so you need a thermometer so that you can regularly check to make sure everything is within acceptable parameters. You can get one that hangs off the tank’s side or a stick-on thermometer that is left on the outside of the glass.

Buying a thermometer can be a bit tricky because they are not always accurate. Look for one that provides an average temperature because it is more likely to be accurate.


Fish thrive when their tank accurately reflects their natural environment. This includes providing simulated day-night cycles through the use of tank LEDs. By providing lights for part of the day, you can help your fish develop feeding and sleep schedules to keep them healthy.

LEDs are the most common types of lights included with tanks. They give off great light, do not take up much power, and are easy to replace. You can also get stand-alone lights or light bars for your tank as an add-on.


The substrate is going to serve a couple of different purposes. It gives your fish a place where they can burrow and can reduce stress for your aquatic pets. Multi-colored gravel is the most common type of substrate used in aquariums.

The gravel at the bottom of the tank will also act as a filter and catch some of the debris in the water. You will need to clean it regularly. Good bacteria live in the substrate, and it is vital for the ecosystem of the tank, so you will need to make sure that whatever substrate you choose is meant to be used in a residential fish tank.

Air Stone

Air stones can be made from several different materials, including wood or limestone. They eliminate large air bubbles that can cause problems for your fish. Whether you have a filter or not, the air stone will improve the oxygenation of the water. Air stones should be left on all the time for the best effect, but they do often accumulate algae inside gaps in their surface, so they will need to be replaced regularly.

Test Kits

Many aquariums come with a test kit that will help you determine the ammonia level in the water. You will need to regularly use test kits to check the water content to know when it needs to be changed. Most tanks will need to be tested at least once every four weeks.


Any stand or surface you use needs to safely handle the tank’s total weight with the water, substrate, and other materials. You can buy a stand, build one, or use something you already own, like a table or desk. The entire tank should be able to fit onto the surface of whatever you choose as a stand.

How to Choose the Best 20 Gallon Aquarium

There several important factors to look at when choosing your aquarium. You want to make sure that it will be a safe place for your fish to live.

Type of Fish you Plan to Stock

Before purchasing any fish for your tank, it is critical that you research which breeds get along well together. Otherwise, you run the risk of buying fish that will attack each other over territory or even eat each other. You should be aware of any special needs they might have in terms of accessories like hides.

Some fish need to be in larger schools; otherwise, they will grow distressed and sickly. Others require solitude. You need to look up the details of the fish you would like to include in your new tank.

Location in Your House

There are a couple of criteria to keep in mind when looking around your home or office for the perfect place to set up your aquarium. Fish are delicate and do best when they are not subjected to a lot of movement or noise, so choose a place away from high traffic areas. Here are a few things to consider when looking at different locations in your home.

  • Are there enough wall sockets nearby to plug in all of the equipment?
  • Loud noises and heavy vibrations are not great for fish and can shock their system, causing distress and early death. Avoid placing the tank near speakers, doors, windows, or entries.
  • You will be doing routine cleaning, daily temperature, and equipment checks, and the light switches will need to be accessible. Cleaning requires removing some of the water and replacing it, so you will want to be somewhat near a room with a sink.
  • Regular direct sunlight can cause several issues, including increasing the rate of algae growth, so you will want to avoid natural light in places like in front of windows.

Glass vs. Acrylic

There are some advantages and disadvantages to consider with glass and acrylic tanks. Overall, the glass will look better and last longer. In contrast, acrylic is more affordable.

Glass is sturdier, less likely to hold scratches, and easier to clean. Acrylic tends to turn yellowish over time and can get cloudy if it is scratched during regular maintenance, but it works well as a temporary first tank.

Your Budget

Have a budget in mind before you start shopping; otherwise, you run the risk of buying overpriced or unnecessary items. When coming up with how much you are willing to spend, be realistic about the cost of the tank and the variety of accessories and necessary equipment that you will need to set up a comfortable habitat for your new fish to live in. If you skimp on the things the fish need to stay healthy and happy, they may not last long because most are quite delicate and prone to shock.

How to Set Up a 20 Gallon Aquarium

The tank setup is straightforward once you have all the equipment and accessories. Whenever you get a kit, make sure you follow the setup instructions that come with it. Here is one set of steps for setting up a standard 20 gallon fish tank.

  1. Make sure all the equipment, the tank, and any decorative items and substrate are clean. You should rinse them with water but not use any cleaning solutions because they can be toxic to fish.
  2. Set up the aquarium in the location you have chosen for it and then put in the substrate and any other items such as rocks, artificial plants, and other decorative items.
  3. Next, you will fill the tank with room temperature water. Use a water conditioner like Tetra AquaSafe to make sure it is safe for fish.
  4. Attach all your equipment like your heater and filter. Before turning the heater on, make sure that it is the same temperature as the water.
  5. Set up the top of the aquarium and plug everything in. Be careful that cords stay away from the water.
  6. Let your tank sit with everything working but no fish for several days to give good bacteria time to settle into healthy colonies within the substrate.

Introducing fish comes with its own set of steps.

  1. Only introduce a handful of fish at a time rather than dumping them all in at once if you plan to have several different types.
  2. When you bring fish home, let the bag they are in settle at the top of the tank. After around 5 minutes, insert a little tank water into the bag, close it again, and sit in the tank for 15-20 minutes until the water inside matches the tank’s temperature. Then let the fish out to reduce the chance of your brand new fish getting a dangerous shock to its system.
  3. Leave your fish in quiet to get familiar with their new environment. Fish are skittish and easily frightened, so it is best to give them 24 hours to get acclimated. It is unnecessary to feed the fish during that time, and they will probably be too nervous to eat anyway.

Frequently Asked Questions

Below are answers to some of the frequently asked questions about 20 gallon aquariums and how to make sure you fill it with the right type of fish.

The tank will be filled with a variety of decorative and necessary items that will take up space. There is no standard answer for the limit of how many fish you can have in a single aquarium. The amount of fish you can fit in a 20 gallon tank depends on many factors, including the following.

  • Specific needs of the fish you choose to buy.
  • What type of filtration system you use, and how well it keeps the water clean.
  • The level of oxygen in the water.
  • The physical size of the fish at maturity.
  • How much extra space you need for decorations and equipment.

We previously mentioned the rule that a fish needs a gallon of water for every inch of length. That is a generalization that fits many types of fish but not all. Some fish need more space than others. You will want to research the different breeds before purchasing any to make sure that however many you buy can live comfortably together as a group without infringing, getting territorial, or suffering from stunted growth.

Your tank’s shape will also play a part in how many fish you can add to your tank. The oxygen content depends on how much surface area there is, so thin, tall 20 gallon tanks will sustain fewer fish than shorter, wider aquariums. A one-inch fish needs twelve square inches of surface area to get adequate oxygen.

There is a wide variety of fish that can live and grow comfortably within a 20 gallon tank’s confines. While some fish get along well, others will not, so before purchasing multiple types of fish, make sure they can cohabit safely. Some of the most common freshwater fish that will fit in a 20 gallon aquarium are listed below.

  • Tetras
  • Guppies
  • Bettas
  • Albino Cory
  • Platies
  • Swordtail
  • Rainbow Shark
  • Glofish
  • Danios
  • Goldfish
  • Dwarf Gourami
  • Rasboras

Keep in mind that most of these fish are social creatures that do best within small groups. Some tropical species will fit in a 20 gallon, but they take specialized care. For first-time aquarium owners, we recommend freshwater fish.

Final Thoughts About 20 Gallon Aquariums

Start with a budget in mind and make a list of features that will be necessary for whatever type of fish you would like to own. You can use these as a guide for determining which 20 gallon tank will be right for you. Then you will need to get accessories, decorations, and supportive equipment that will help create a beautiful, comfortable home for your new fish.

Be careful when setting up your tank and introducing your new aquatic friends to give them the best chance at a long, happy life. Tanks require regular upkeep, which means most aquariums need cleaning every two or three weeks. The satisfaction of creating a beautiful setup for your fish will amplify the enjoyment you will get out of watching these beautiful creatures thrive. 

Looking for more gear for your aquarium? Head over to our Aquarium Gear section to see more reviews.

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