The Best 20 Gallon Aquariums – Reviews and Ratings of The Top 20 Gallon Fish Tank Kits

When you need a new 20 gallon fish tank – or just want to start up a new system – you need some solid reviews to look into.

There are hundreds of options on the market, but you can easily sort through them by knowing some of the best brands, finding the right features to look for to fit your setup, and of course, reading reviews.

But since there are so many options, I’ve done some research (based on what I know from actually being a long time fish keeper, combined with in-depth research) for you to help knock out the poor options and find just the best.

But before we look there, let’s keep a few things in mind as we shop for the best 20 gallon fish tank.

Best 20 Gallon fish tank Quick-Find Table

Important Equipment to Get for Your New 20 gallon fish tank setup

You can set up your 20 gallon aquarium for either freshwater or saltwater use and apart from things like specifics for reptiles and crabs, most of the points are the same.

There are, however, a few differences you’ll notice below.

Each item is categorized by type of aquarium it’s for, so just look for your marine or freshwater needs.

Filter: Both

Even if you have the best tap water in the world, your fish tank needs purified water.

Saltwater and freshwater fish will become unhealthy and can die if they live in straight-up, unfiltered tap water.

Author note: Fish – whether freshwater or saltwater, goldfish or exotic tropical – need fresh, clean water to breathe in just as we need smog-less skies.

Check out our reviews of the best filters here.

Heater: Saltwater Yes, Freshwater Possibly

If you’re keeping cold water fish like goldfish and live in a reasonably warm environment, you may find you don’t need a water heater for your aquarium.

However, nearly every tank will be better off with one.

Most popular fish for aquarists are tropical and semi-tropical fish, which means room temperature water that drops below about 68-degrees Fahrenheit can make your fish ill – or worse.

Check out our reviews of the best heaters here.

Lights: Both

Enjoying your aquarium is the primary reason you’re setting one up. If you can’t see inside the aquarium, chances are you won’t enjoy it much.

Top tip: But more importantly, your fish and aquatic plants need light to grow and thrive. And that means the right lighting system.

Just like humans need sunlight to get vitamin D and keep those happy feelings, fish need light as well to remain happy and healthy. And plants – well, they use photosynthesis which comes from light.

Check out our reviews of the best LED lighting systems here.

Substrate: Most

Nearly every kind of aquarium needs substrate like gravel or sand. The substrate gives your live plants somewhere to grow from, a place for waste to lodge before cleanings, et cetera.

Top tip: Plus, honestly, a pretty glass gravel just looks stunning in a marine aquarium. 

Hood: Both

Sometimes, you’ll find folks say hoods are optional. However, I really wouldn’t recommend going without.

Some species of fish jump – like Firefish and Killfish, for example – some don’t.

Author note: Hoods also provide protection for objects falling into the tank, reduce cleaning issues – no hood equals lint, dust, and more getting in – and keeping predators out, like my cat.

Protein Skimmer: Saltwater

For those keeping a marine tank, you’ll want a protein skimmer to reduce waste and keep things clean in there.

They come designed for various sizes, so be sure to thoroughly read reviews to make sure you’re getting the right one.

Check out our reviews of the best protein skimmers here.

Sea Salt Mix: Saltwater

If you have a marine aquarium, you also need a sea salt mix.

Your purified water doesn’t have that sodium your Clownfish needs, so be sure to find the right brand that’s safe and healthy to use for your fish.

Air Stone: Both

Not all fish tanks need an air stone, but they do help to aerate the water, clean the water a bit, and generally add some attractive fun to the tank with their lovely bubbles.

Just be sure to clean them often to keep them running well.

Check out our reviews of the best air pumps here.

Test Kits & Thermometers: Both

Every aquarium needs to be kept in balance with the life of the aquarium critters. You’ll need to have some kits on hand to make sure things are in tune, as well as a thermometer to make sure the water temperature is acceptable for Nemo.

Kits you probably need include:

• pH
• Nitrites
• Nitrates
• Ammonia
• Phosphates

Check out our tank cleaning article here, where we talk about what kits we love best.

Decorations: Both

Of course, since the main reason you keep an aquarium, you want it to be attractive.

While those colorful Discus fish naturally add some pop and flair, the decorations you keep in there also help to make things more fun for viewing – as well as help keep your fish happy.

Top tip: Be sure to select overhangs, caves, treasure chests, or other décor items that work well with the type of fish you’re keeping.

Let them do double duty by providing shelter and eye-popping attraction, if you can.

Fish Net: Both

And finally, you need a fish net.

When you transfer fish from the old home – whether that’s a pet shop or quarantine tank – you need to hoist them between water bodies safely.

Just be sure to acquire a net large enough to safely carry your largest fish.

How to Choose the Best Tank

When you get to shopping, you’ll want to keep a few things in mind to guarantee you actually get a high-quality 20 gallon fish tank.

The Right Size

While not as commonly an issue as the 10-gallon tank, sometimes a 20 gallon tank just isn’t the right size for your fish keeping needs.

Be sure to verify what the smallest size tank recommendation is for the given creatures you plan to keep – whether that’s a betta, land crab, or Killifish – and make sure that calculation includes all of them.

Fits Your Budget

It’s easy to go over budget in fishkeeping. We aquarists love our aquariums!

But if you find yourself looking at aquariums that cost more than you can safely afford, you’re going to be in trouble, since it’s not just the best 20 gallon fish tank you’ll need to purchase to get things going.

Types Fish You Stock

Of course, the type of fish you stock in your aquarium also effect the type of aquarium you get. Some 20 gallon fish tanks come in the standard long shape, while others come in square cubes, lengthy pillar-style tubes, et cetera.

Some fish need a wider feel, while others won’t mind a more interesting design. Be sure to study the type of space your fish needs before choosing the aquarium.

The Space They Take Up

Another important aspect is making sure you get the best 20 gallon aquarium kit for the space you have to work with.

If you’ve got a tiny apartment with little counter space and even less space for a stand, you’ll need to find something that works within your parameters.

If you have large spaces around the house and have plenty of room to keep a few 20 gallon fish tanks around, you’ll be fine with anything unless you’re aiming to place it in a specific space.

Just think through your space before shopping and make a few notes on what your guidelines need to be.

Your Level of Experience

Finally, and potentially the most important thing to consider as you shop for a 20 gallon aquarium kit is how much experience you have with keeping fish.

If you’re an old pro, you don’t have anything to worry about besides the quality of manufacture and precise measurements.

But if you’re a newbie aquarist, you’ll need to keep in mind your experience level to help make sure you get the right setup.

Some tanks are perfect for beginners, while others are more sophisticated and require more experienced aquarists to set them up.

Reviews of the Best 20 Gallon Aquariums

The Marina LED Aquarium Kit is one of the absolutely highest recommended 20 gallon fish tank setup choices on the market.

The glass aquarium comes with a solidly built glass fish tank that comes with the Marine Slim S20 filter, lighting system, water conditioner, and more.

Basically, this kit comes with everything you need to get started and it’s all high-quality.

The kit is almost complete.

You’ll just need to purchase testing kits, live plants, and a heater, plus, of course, fish, to have everything you need to start your aquarium.

You’ve even got some supplements and fish food samples included. Be careful to read the ingredients before feeding, though, to be sure it’s the right kind of food for your fish.

Here’s the breakdown:

• Dimensions: 24” L x 12.5” W x 16.5” D
• Weight: 37.4-pounds empty
• Type: Freshwater, saltwater
• Materials: Glass
• Includes: HOB filter, replacement cartridges, LED lighting system, canopy, fish food samples, water conditioner, cycle biological supplement, fish net & care guide

One of the best things about this kit is the lighting system. The LED lighting system simulates natural daylight and is incorporated into the canopy.

The bulb is bright enough to give the needed affect, but not so bright that it feels disruptive to your fish or home. It’s also energy efficient and adds some color where other lighting systems may be glaring or dull.

Another great thing about this kit is the Marina Slim S20 filter. It’s a hang-on-back – or HOB – filter with quick change cartridges that make it even easier to care for your tank.

The filter is powerful enough to keep the tank clean and clear for a good long while.

Overall, the whole kit is quite affordable for most and comes with high-quality accessories that it would be hard to get for the same or less separately.

>> Tap Here to Read More Reviews and See Today’s Price on Amazon.com <<

The Tetra 20 Gallon Aquarium Kit with filter, heater, lights, and plants is probably the most complete kit on the market.

It comes with practically everything but the fish. So, if you need just a one-stop shop kit, you’ve found it in this well-trusted brand.

This kit is perfect for a beginning hobbyist, no matter the age. It’s super easy to set up and use, keep clean, et cetera, especially since it has everything your fish needs.

Here’s the breakdown:

• Dimensions: 24.2” L x 12.4” W by 16.7” D
• Weight: 34.9-pounds empty
• Type: Freshwater or saltwater
• Materials: Glass
• Includes: Tank, hood, UL heater, heater, color-changing LED, 2 multi-packs of artificial plants, 1 blooming white Anemone

Personally, I’m not a fan of artificial plants, but if you’ve got a black thumb like I do, this kit is great since it comes with a variety of options, including a blooming Anemone.

It’s also great for kids and teens who may not be quite able to take on the full responsibility of fish and plants at once.

>> Tap Here to Read More Reviews and See Today’s Price on Amazon.com <<

Another fantastic starter kit is the Aqueon 20 Gallon Kit. From another brand as well-trusted as Tetra, Marineland, and Fluval, the Aqueon offers a fairly full kit that will help any beginning aquarist get setup in no time.

Aqueon’s 20 gallon aquarium kit comes with a low profile, full LED hood that has built in vibrant, cool white LED lighting built-in.

Plus the QuietFlow 10 LED PRO power filtration system has a red light indicator that let’s you know when the cartridge needs changing.

It’s a quiet filter that won’t disrupt your home space – even in bedrooms.

Here’s the breakdown:

• Dimensions: 24.2” L x 12.5” W x 19.5” D
• Weight: 33-pounds empty
• Type: Freshwater or saltwater
• Materials: Glass
• Includes: Glass tank, full hood, lights, filter, pre-set heat, sample fish food, water conditioner, fish net, stick on thermometer

The Aqueon LED kit comes with some great accessories.

The heater, however, is pre-set, so make sure to verify that the fish you plan to stock your aquarium with will do well with the pre-set temperature of 78-degrees Fahrenheit.

Most fish do well with this, but there are some cold water critters – think goldfish – that need something a bit cooler.

>> Tap Here to Read More Reviews and See Today’s Price on Amazon.com <<

If you don’t need the full set up, and are looking for the best 20 gallon long aquarium starter kit instead of the boxier shapes, you should look into the Aqueon 20 Gallon Long fish tank.

This tank is modestly weighted, 30.25-inches long for a unique feel, and is very well-built.

This shape is also best for certain species of fish, so may be your top pick for the shape alone.

The Aqueon uses high-quality glass with clean silicone edges, available in black or clear and is made of distortion free glass, meaning you get a sharp, clear view of your fish and critters inside the tank.

The frame is made of solid black plastic and the whole thing is tightly sealed with commercial grade silicone to prevent leaks.

Here’s the breakdown:

• Dimensions: 30.25″ x 12.5″ x 12.75″ 
• Weight: 22 pounds empty
• Type: Saltwater, reef, or freshwater
• Materials: Glass with silicone edging/seals
• Includes: Just the tank

Long aquariums are not only great for a better view, but they’re better for the gas exchange due to the length versus height ratio.

That helps to make this basic aquarium an excellent option.

This fish tank is made of extremely high-quality glass and sealant, so you won’t have to question if this will keep the water and fish in.

You do need to be aware that it is only the aquarium on our list, however, without a kit, which means it’s a bit pricier than many other options.

However, the quality of material and manufacture makes up for it, as you know you’ll own and use this for a long time.

>> Tap Here to Read More Reviews and See Today’s Price on Amazon.com <<

If you’re more feeling the acrylic aquarium and need an easy kit for fish care, the SeaClear Aquarium Combo Set is your best bet.

It’s simple to set up, easy-to-use, and fits just about anywhere comfortably since acrylic isn’t as heavy as glass.

Though the kit doesn’t come with a lot of accessories, it does come with a clear lid. For those who plan to keep their aquarium in a central viewing location, this is a great option as folks of all heights can enjoy it.

Plus, with the intense clarity of acrylic, you’ll have more viewing pleasure all around.

Here’s the breakdown:

• Dimensions: 24” L x 13” H x 16” D
• Weight: 19.4-pounds empty
• Type: Freshwater or saltwater
• Materials: Acrylic
• Includes: Tank, reflector light fixture – bulbs not included, clear acrylic top

Acrylic tanks are more impact resistant and less prone to chipping, which makes this one a great option for homes with kids and pets – or clumsy spouses – who tend to bump into things a lot.

They are, however, a bit harder to keep scratch free. If you choose this aquarium, be sure to get proper soft cleaning supplies to avoid ruining the stunning clarity.

>> Tap Here to Read More Reviews and See Today’s Price on Amazon.com <<

20 Gallon Fish Tank Set Up

Once you’ve chosen your 20 gallon aquarium and brought it home – or ordered it in – you’re ready to set it up. Below you’ll find a short video that gives some visual detail on how to do this, and a quick overview from me.

1. Gather up your equipment into the basic area where you’ll set up your aquarium.
2. Then, clean out the aquarium thoroughly. Let it dry completely and make sure all cleaning residues from soaps are gone before you begin.
3. Now, thoroughly clean your gravel or sand by rinsing with clean, filtered water. I prefer grabbing a few gallons from the local grocery for a quick, easy job of this.
4. Next, you’ll put the substrate into your tank and evenly spread it out as needed. Be sure to never use rocks or sand you find outdoors as they can carry parasites and diseases that will make your aquarium sick.
5. Now, add in your live plants and decorations. Position and reposition them until you like the way they look from your best viewing angles.
6. Now, fill your tank with purified water. Be sure to follow the instructions on how to filter the water properly. Add marine salt, if needed.
7. Next, position lighting, pumps, air stones, et cetera within and around the tank.
8. Get the temperature up to specs for your fish.
9. And now that everything is ready, you can introduce your fish to the aquarium.