Best 20-Gallon Fish Tank & Buyers Guide

Setting up an aquarium comes with many benefits. Installing a fish tank in your home is not only for décor purposes but rather your own window to another fascinating world that can make you appreciate and understand the environment and its precious life. This is more than observing another world. Today, it is quite easy to create it yourself with some useful tips and tricks and the right products.

If you are just diving into the underwater world, you should know the basics. When it comes to aquariums or fish tanks, bigger is not necessarily better. While a 50-gallon fish tank might look great, it might not work for your space. Today, we are focusing on the 20-gallon fish tank kits. These are perfect for beginners, as they are large enough to hold various fish but small enough for easier maintenance.

Fish are thought of as easy pets when it comes to caring and maintaining. While this is true most of the time (depending on the species), setting up an aquarium in your home is a large project. However, with the right tools and information, you can simplify your work and achieve great results.

A fish tank requires all sorts of tools and items, but today, you don’t need to purchase every single item separately. It is crucial to distinguish between essential and non-essential items to not overbuy or buy unnecessary things. Luckily, you can find full aquarium kits that are ready to use nowadays, meaning they have everything you need, minus the fish.

Even so, it’s best to learn as much as you can before buying such a kit, as you might still need additional items and skills to keep your fish world happy and healthy. Purchasing aquariums can get expensive, so the more you know about what is essential, the more you can adjust your budget and pick the right items for your needs without breaking the bank.

That being said, here are the most important things to look for in a 20-gallon fish tank kit.

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Our Favorite

Customers Choice

Aqueon LED Aquarium Kit

Marina LED Aquarium Kit

Tetra Aquarium Fish Tank Kit


27.25” x 15.75” x 21”

30” x 18” x 22.3”

24.2” x 12.4” x 16.7”


20 gallons

20 gallons

20 gallons


33 pounds

35 pounds

34.9 pounds








Glass (scratch-resistant)

Our Rating

Aquarium Materials and Size

In terms of size, we will talk about 20-gallon tanks, as they are more likely to fit a dorm room or hallway.

In terms of shape, it is best to avoid the tall tanks. Look for width, not height, as with wider tanks, your fish will have enough room to swim (laterally). There is another reason why you should choose wider tanks. Your fish need oxygen, just like us humans. The larger the water surface, the more oxygen exchange you will have. Not to mention that, if you want to have a larger fish variety, a tall tank will make that impossible.

When it comes to materials, there is glass and acrylic. Glass aquariums are usually the way to go, as they are more durable and sanitary. However, suppose you have small children and plan to install your aquarium within their reach. In that case, acrylic might be a better temporary option, as it doesn’t break.


Usually, complete kits come with everything you need, including a hood and lighting. However, if you buy your aquarium separately, you should always check for a lid. If it doesn’t come with a top, it can be sold separately, so check out the options. Lids or hoods are essential parts of fish tanks, as they prevent the fish from jumping out. Lids can be made of plastic (especially if they come with incorporated lights) or glass. The glass lids allow more natural light to pass through and are easier to clean and maintain. However, plastic hoods weigh much less, are more affordable, and less likely to break.

Another tip is to look for hinged hoods, as they make your life more comfortable overall. A hinged hood means easy access in the tank, as well as not having to temporarily remove the light while you clean or feed your fish. Lids that are not hinged and have the light incorporated tend to be flimsier and add more inconvenience.


Although you can still find fluorescent and incandescent lights on the market, they are starting to lose the battle. LEDs are now accessible. They produce more brightness with less power consumption. They last longer, and you can even find some dimmable options to better control your environment. Most fish tank kits already include some type of lighting packaged in the lid. Depending on your tank and what you are trying to accomplish, you can purchase the light separately. However, it is best to look for incorporated LED lights when you are buying an aquarium kit. This way, you can save a bit, considering there are still additional items you might need to purchase afterward.

Filtration System

Since your tank’s environment needs to replicate what naturally happens in the sea world or the rivers, the water needs to be filtered. Since there are no natural currents in there, it requires the appropriate filtration systems. Your fish need healthy filtered water just like we need fresh air. Think about the smog and how unhealthy it is for our lungs and overall health. That is what you should think of before buying a filtration system for your aquarium. The bottom line is that if there is one item you can splurge on, we encourage you to spend on filtration if you want your fish to be healthy and happy.

There are three Filtration Categories:

Biological Filtration

This term refers to the beneficial bacteria that grow on the surfaces that are submerged in the aquarium. Your fish produce ammonia as a respiration process result, as well as waste from the digestion of foods. There are also nitrate and nitrite that can be harmful to your underwater environment. These beneficial bacteria process the waste into less toxic by-products. Live rock is one of those biological filtration systems that grows and hosts these beneficial bacteria that will filter out these harmful by-products and provide a thriving environment for your fish.

Mechanical Filtration

This is the most straightforward filtration principle of all. It consists of a filter that traps all the waste, remaining uneaten food particles, debris, and decayed plant particles in the water. Some mechanical filters contain pads, some work with sponges, or even filter wool. This is the first and most basic type of filtration that you should know of.

Chemical Filtration

This filter removes organic pollutants that could not have been removed by the mechanical and biological filters. What kind of pollutants are we talking about? Organic particles, proteins, acids, or different air elements can enter the fish tank at the water’s surface, such as perfume, nicotine, pesticides, the medication used to treat the fish, heavy metals, etc.

Activated carbon, Zeolite (a natural volcanic rock), resin, and other such materials can remove the unwanted pollutants.

Nowadays, you can find all-in-one filtration systems that are covering all filtration methods. Make sure to always read the descriptions and specifications before investing in a solution like this, as you might still need to make separate purchases to ensure a clean environment for your fish.


Depending on the type of water and species of fish you want to stock (saltwater vs. freshwater, tropical fish, etc.), you might need a heater. For freshwater, most fish require a temperature of 74-77 degrees Fahrenheit. If your house temperature is stable and doesn’t fluctuate, you would not need a heater. However, if you live in a cold environment, you need to buy a heater, so your fish won’t get sick.

Now that you know what to search for, let’s look into some of the best 20-gallon fish tank kits and aquariums that would look great in your home.

The Best 20-Gallon Fish Tank

1st Tetra Aquarium Fish Tank Kit


  • Dimensions: 24.2” x 12.4” x 16.7”
  • Weight: 34.9 pounds
  • Type: freshwater/saltwater
  • Material: Glass (scratch-resistant)
  • Includes: 20-gallon fish tank, hinged hood, UL heater, LED lights, 2 multi-packs of artificial plants, 1 Boxwood plant mat

If you are new to aquarium setups or you prefer the all-in-one approach, this brand provides everything you need to start your own underwater world at home, hassle-free. Instead of buying everything separately, making sure that every part fits accordingly, this 20-gallon fish tank comes with everything you can imagine.

You will receive a great-quality 20-gallon glass aquarium that is made in the US and is scratch-resistant. The brand stands behind its products, so you will also get a lifetime warranty when you purchase this kit.

In the package, you will find a Tetra 100-Watt heater that keeps the environment nice and healthy for your fish. Additionally, you also receive a Tetra Whisper 20 filter that is easy to install and use. An LED hood is also part of the package and ensures a natural lighting environment and saves energy. The hood is also sleek and low-profile, so it looks great, and it is perfectly adapted for the 20-gallon tank. You also get a stick-on thermometer.

Finally, you get an artificial Boxwood Plant Mat and two artificial plant multipacks to add shelter and lots of color to your aquarium. All you need to add now is gravel and fish, and you are all set up.


  • All-in-one package – it includes everything you need to get started
  • Lifetime warranty
  • Quiet filter
  • Scratch-resistant glass
  • Hinged hood


  • Artificial plants are not the best option. You might want to switch them with real ones.
  • The filter isn’t the best, and it seems to not last for long.
  • The thermometer is stick-on, so not much reliability.
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2nd Red Sea Max Nano Aquarium



  • Dimensions: 18” x 18” x 18”
  • Type: freshwater/saltwater
  • Material: ultra-clear rimless glass
  • Includes: removable surface skimmer, ReefLED 50 LED Light Fixture – 50 Watt, ReefBeat App for lighting control, circulation pump, integrated power center, mechanical filtration and filtration media, automatic top-off with freshwater reservoir.

If you are on the hunt for the best-looking, technology-equipped 20-gallon aquarium, and you are willing to up your budget, it can’t get better than this.

This incredibly looking aquarium is made of 8 mm ultra-clear and rimless glass that provides the best viewing experience. The open-top design allows the REEF-SPEC LED light to flood the water in the most efficient way. The light uses ultraviolet, violet, and blue LEDs. It has a separate Moonlight channel for a low level of light at nighttime. All your lighting scenarios can be controlled and customized via the ReefBeat App.

It also has a pump that recirculates the entire water volume 12 times per hour through the filter system. Additionally, it has a control unit for the protein skimmer and a circulation pump. The Automatic Top-Off unit holds 4 gallons of freshwater and allows the aquarium to run for three days unattended.

The Nano Skimmer has a built-in silencer. The integrated control unit switches the pump on and off when you are feeding or doing the maintenance.

That being said, the price is obviously higher than any other 20-gallon aquarium kit on this list. However, you get state of the art technology, top-notch design, and a durable and reliable piece of equipment you will have for life.


  • Plug & play system
  • Rimless and ultra-clear glass
  • State of the art LED technology
  • Dedicated app to control the environment
  • Automatic top-off unit that keeps makes the aquarium self-sustainable for three days
  • Integrated control unit
  • Very potent pump
  • Nano protein skimmer with built-in silencer


  • Expensive
  • It doesn’t come with a heater
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3rd Marina LED Aquarium Kit


  • Dimensions: 30” x 18” x 22.3”
  • Weight: 35 pounds
  • Type: freshwater/saltwater
  • Material: Glass
  • Includes: 20-gallon fish tank, hood (canopy), LED lights, HOB filter, water conditioner, cycle biological supplement, fish net, fish food samples

This is another all-in-one aquarium kit that is perfect for beginners. In this kit, you will find a 20-gallon fish tank made of glass, which is always great news. Additionally, you get a much-needed clip-on filter that will purify your water. It is easy to use and change up the cartridges when the maintenance is due.

Also, you have an LED light incorporated into the hood for a natural and energy-saving source of light. If you worry about the water quality, this kit features a water conditioner that makes tap water safe and healthy for your fish. You will also find a Cycle Biological Supplement to create a well-balanced environment instantly.

This kit truly has some essential items for an easy aquarium setup. You even get a fish net made of soft mesh to protect and scoop out your fish. Moreover, the kit includes fish food samples for an easy feeding start. Just make sure you check if the type of food is compatible with your fish species and diets, and you are ready to start your aquarium.

Of course, you might need additional items, like a heater, testing kits for your water, and some live plants. Still, all in all, this aquarium kit has pretty much everything you need to get started.


  • Almost everything you need for an easy start
  • The filter is quiet
  • Fish food samples
  • Great quality glass and sturdy construction


  • The lid is not hinged, so you have to remove it, which eliminates the LED lights too, since they are attached to the cover.
  • The lid makes the filter sound loud (the filter itself is whisper quiet).
  • The filter might be weak for this 20-gallon tank.
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4th SeaClear Acrylic Aquarium


  • Dimensions: 24” x 13” x 16”
  • Weight: 20 pounds
  • Type: freshwater/saltwater
  • Material: Acrylic
  • Includes: 20-gallon fish tank, clear acrylic top, reflector light fixture (light bulb not included)

Suppose you have children and you want to avoid accidents, or you just love the look of a crystal-clear aquarium that has no edges. In that case, this acrylic fish tank will give you an endless view of the underwater world.

Even though this fish tank doesn’t include any accessories, it is one of the best 20-gallon aquariums made of acrylic. This material has some benefits that you might like.

First, it looks great because it has no corners or lines. Acrylic weighs much less than glass, which means that it is easier to handle. You get more viewing angles, and it is more resistant to impact and less prone to chipping. All decorations inside will pop in this clear aquarium, and that’s what we like most about it.

However, it has its downsides, obviously. Acrylic is hard to keep scratch-free. It is also harder to keep clean over time due to the more porous material that tends to grab onto debris.

You will find the option to get a clear lid or a black plastic hood that has room for fluorescent lighting. However, you won’t get any lighting bulbs inside. Everything you want to put in there, you have to purchase separately. Also, the top is non-removable. It just has openings for food, filters, and heater. This makes it hard to do maintenance or catch the fish.


  • Great looking aquarium. More view angles.
  • It weighs less than glass
  • Impact-resistant and less prone to chipping


  • A bit pricy for a clear acrylic tank
  • Hard to keep scratch-free
  • Fixed top – hard to do maintenance
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5th Aqueon LED Aquarium Kit


  • Dimensions: 27.25” x 15.75” x 21”
  • Weight: 33 pounds
  • Type: freshwater/saltwater
  • Material: Glass
  • Includes: 20-gallon glass tank, hood, LED lights, filter, pre-set heater, water conditioner, fish food sample, stick-on thermometer, fishnet

This is yet another full kit to get you started on your aquarium setup. It comes with everything you need, and it is easy to install.

This time, the aquarium is made of glass, and it has no rims, so nothing will distract you from the beautiful view. You will get an integrated LED cool lighting along with the hood. Also, you have a 10 LED PRO power filter with a great feature: a red light will flash when it’s time to change the cartridge, so you will never have to guess again.

Another useful item is the 100W heater. It comes pre-set at 78 degrees Fahrenheit to keep your fish healthy and happy. You also get a water conditioner, a stick-on thermometer, some fish food samples, and a useful fishnet.

The downside is that the hood is not hinged, so you remove the integrated LED light when you remove it. Another potential problem is that the LED doesn’t have a waterproof cover, so pay attention to the splashes, as it can stop working If it gets soaking wet.


  • Complete aquarium kit with everything you need
  • The filtration system is quiet
  • Fish food samples
  • Sturdy construction


  • The hood is not hinged
  • LED lights don’t have a waterproof cover
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6th GloFish Aquarium Kit


  • Dimensions: 27.88” x 16.13” x 20.38”
  • Weight: 34.15 pounds
  • Type: freshwater/saltwater
  • Material: Glass
  • Includes: 20-gallon glass tank, LED hood, Tetra mini UL heater, Tetra Whisper 20 filter, GloFish 13” LED light stick, 1 yellow anemone, 2 artificial plant multipacks, water conditioner sample, fish food

If you like the neon-look, this aquarium is for you. This 20-gallon fish tank kit has a special feature that makes it shine – literally. For your 20-gallon glass tank, you get blue led lighting that creates a neon display as it lights up the artificial plants you receive. This fluorescent look is something that you either love or don’t, but it has many other things to offer, as well.

This is also a complete starting kit for your underwater world. It includes an LED hood, A tetra mini UL heater, a quiet filter, and more.

The great thing is the price point, as it is much more affordable than similar aquarium kits. You will also find a water conditioner sample and some artificial fluorescent plants to help you pull the look together.

Like all things, this one has its downsides as well. The hood is not hinged, and it can be flimsy, the plastic plants look a bit cheap, and some users have had some trouble with the filter, as it clogged quite fast. However, it’s a great aquarium setup for this price, even if you want to tweak it along the way.


  • Great price point
  • Nice neon look
  • It includes everything you need
  • Fish food included


  • The plants can look cheap
  • The hood is not hinged, and it’s a bit flimsy
  • The filter can get clogged quickly
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7th Tetra Color Fusion Aquarium


  • Dimensions: 27.88” x 16.13” x 20.38”
  • Weight: 34.35 pounds
  • Type: freshwater/saltwater
  • Material: Glass
  • Includes: 20-gallon glass tank, LED hood, 1 UL heater, Tetra Whisper 20 filter, 1 color-changing LED light, 2 Wonderland Plant Multipacks, 1 blooming white anemone

This aquarium is another excellent choice for beginners. It is a combo pack that includes most of the necessary items to get started.

The glass aquarium is worth every dollar, especially considering that it comes at an affordable price point. It is durable, and it includes some excellent features that will add visual interest to this setup. The LED light is color-changing, so you can customize the way your fish tank looks by paying a cycle or choosing a specific color.

You get a pre-set heater (78 F), a water filter, and some artificial plants to start decorating and creating your desired look. However, we always recommend getting real plants, as plastic tends to look cheap. All in all, this is a great starting point, and you can always add to it as you go.


  • Affordable, yet durable option
  • Glass tank
  • It comes with all the essentials
  • Color-changing LED


  • The artificial plants look cheap
  • The heater has no control option
  • The filter starts to get noisy after a while
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8th Aqueon Black Tank Aquarium


  • Dimensions: 30.25” x 12.5” x 12.75”
  • Weight: 22 pounds
  • Type: freshwater/saltwater
  • Material: Glass
  • Includes: 20-gallon glass tank

For those who don’t want aquarium kits but prefer purchasing your items separately, this is a good alternative to aquarium kits.

This aquarium has an advantage: it is longer than it is tall. This allows your fish to have more room for swimming, and it creates a cozier environment. This quality glass construction can be used for various applications, not just for fish. However, it’s a great starting point. It looks great. It’s sturdy and durable, and it comes with transparent edges for better viewing angles.

The price is not low, but if you plan on customizing your aquarium with your items of choice, this long 20-gallon aquarium is perfect for that.


  • Sturdy glass construction
  • Transparent edges
  • Long format for a cozier feel


  • Pricy
  • It doesn’t include other essential items
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Final Thoughts

The best 20-gallon aquarium is the one that acts both like a décor piece but also provides a safe environment for your fish. There is no fish tank kit that will come with every accessory, but the good news is that, if you decide to go with one of these kits, they all have the essentials for an easy start.

A 20-gallon aquarium is the perfect size for almost any space. It’s large enough for a few fish to swim freely, but small enough to fit in a tight space – that’s why we think this size would be a great fit for most of you.

Lastly, it doesn’t matter which fish tank you choose, as long as you’ve got the basics figured out. Be sure to always read the reviews before purchasing and have fun. After all, the fish world is fascinating, and you can always add more to it later on.


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