Cheap 20 Gallon Fish Tank – 5 Budget Choices, Guide, FAQs & More

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Everyone wants a high-quality aquarium for their aquatic pets but you’ll agree with us when we say that the prices for worthwhile fish tanks have gone through the roof as of late. 

Keeping this in mind, we’ve scoured the market to bring you affordable 20 gallon fish tanks that will give you great value for your money. 

In this post, we’ll discuss what makes these fish tanks great and the things you should look out for when buying a 20 gallon fish tank at a modest price. 

Top Pick

If you’re looking for an effective aquarium with a simple, modern design, this is the one. It provides ample space for fish to swim in and comes with great accessories.

Runner Up

This product is especially lightweight which makes it very easy to handle and place. The no-border design makes for unobstructed viewing and the walls are clear.

Also Great

This kit comes with accessories that none of its competitors have. You’ll get everything you require to get started in this kit and the tank itself is very durable and long-lasting.

We tested all kinds of 20 gallon fish tanks and in the end, these three are undoubtedly the best ones from the bunch. 

Now, let’s get into the reviews for the top 5 cheapest 20 gallon fish tanks.

Cheap 20 Gallon Fish Tanks - Best 5 Reviews

1. Best Cheap 20 Gallon Fish Tank - Marina LED Aquarium Kit Review

The Marina LED aquarium kit goes with a simple and elegant design that lures you in. It’s a simple rectangular-shaped fish tank that does everything you need it to do very effectively. Your fish will have ample space to move around and interact with their environment in this aquarium. 

It comes with many accessories including things like water conditioning agent and fish food. 

The filter is very effective and does its job so well that you very rarely have to clean the tank manually. It also has a focus on biological filtration which helps kill toxins in the tank that may be harmful to your fish.

Features of Marina LED Aquarium Kit – Cheap 20 Gallon Fish Tank

  1. Built-in clip-on filter with quick change cartridges
  2. Comes with food and water conditioner samples
  3. Fish net included
  4. Glass aquarium
  5. Built-in LED lighting
  • LED lights are bright but not overbearing
  • Long-lasting durable glass
  • Requires little maintenance
  • Easy to set up 
  • Compact and simple design
  • Quite heavy

If you’re looking for a high-quality tank that does its job effectively and comes with lots of accessories, this product is perfect for you. The LED lighting built into the canopy illuminates the tank brilliantly and it’s very sturdy.

2. Cheap Crack-Resistant 20 Gallon Fish Tank - SeaClear Acrylic Aquarium Combo Set Review

The SeaClear Acrylic Aquarium Combo Set comes in a number of shapes and sizes but their 20 gallon version is by far, the most popular and, in our opinion, the best version they have of this product. 

Being made of Acrylic means it’s very resistant to cracking or leaks and the walls are much clearer than a glass aquarium’s could ever be. You’ll be amazed at how crisp and beautiful your fish’s colors are when you view them in this aquarium. 

It comes with a reflector and a light fixture you can use to hang any type of light that you think is appropriate for the fish inside.

Features of SeaClear Acrylic Aquarium Combo Set

  1. Impact-resistant
  2. Borderless, minimal design
  3. 15-inch light fixture and reflector included
  4. Dimensions: 24 by 13 by 16 inches
  5. Weight: 19 pounds
  • Suitable for both salt and freshwater environments
  • Lightweight
  • Crystal-clear walls
  • Easy to clean
  • Durable
  • Doesn’t come with light. Only a light fixture

If you want a lightweight aquarium that’s easy to handle then this is the product for you. The borderless design gives it a modern aesthetic and it’s very sturdy. 

3. Cheap 20 Gallon Fish Tank with Artificial Plants - Tetra 20 Gallon Complete Aquarium Kit Review

Tetra is a household name when it comes to aquatic products. They make all kinds of high-quality products for fish-keepers and fish tanks are no exception. 

This aquarium kit comes with a ton of additional equipment and accessories. It has lighting that’s integrated into the hood, it comes with a filter that’s effective and works silently, it even comes with a heater and four decorative plants. 

That’s the most accessories in one kit out of all the aquariums on this list.

Features of Tetra 20 Gallon Complete Aquarium Kit

  1. Scratch-resistant glass
  2. LEDs built into the hood
  3. Comes with a mini heater
  4. Built-in filter
  5. Comes with artificial decorative plants
  • Long-lasting
  • LED lights come with a natural daytime effect 
  • Artificial plants help fish relax and reduce stress
  • Filter is quiet
  • Easy to maintain
  • Heater may be too small for the tank

If you want serious value for money and are looking for a kit that comes with everything you need, this is the product you’re looking for. You won’t have to go out and buy any other additional equipment if you get this kit.

4. Cheap Customizable 20 Gallon Fish Tank - OCEANIC SYSTEMS INC. All Glass Aquarium AAG10021 Tank Review

We’ve been talking a lot about aquariums that give you a lot of accessories and essential equipment with them. Now, let’s go to the other side of the spectrum. 

More advanced fish-keepers usually don’t want all the extra equipment that comes in aquarium kits. They want a more tailored experience and want to build their aquarium scratch with equipment they can choose on their own. 

This is a product made for them. It’s a no nonsense rectangular glass fish tank and that’s all you get. It’s a blank canvas for you to attach equipment that you deem appropriate for this fish you’re going to get.

Features of OCEANIC SYSTEMS INC. All Glass Aquarium AAG10021 Tank 

  1. Dimensions: 30.2 by 12.5 by 12.8 inches
  2. Weight: 22 pounds
  3. Resistant to glass bowing 
  4. Black and Oak trim styles
  5. Built to accommodate all kinds of equipment
  • Highly customizable
  • Lightweight for its size
  • Resistant to leaking
  • Easy to handle
  • Simple to clean
  • May arrive damaged according to some reviews

If you’re looking for a barebones aquarium that you can customize completely, this product is definitely it. It’s built to stand up to all types of modification and the glass is crystal-clear and wither-resistant.

5. Cheap Low Power Consumption 20 Gallon Fish Tank - Marineland (Aquaria) AMLPFK20B Biowheel Aquarium Kit Review

We’ve heard a lot about how people buy an aquarium that comes with great, effective shimmering lights, a great filter and effective heater but then, they end up with an electricity bill that has gone through the roof. They’d thought they were getting a cheap deal when they bought the product but in the long run, it’s not cheap at all. 

Marineland keeps this in mind. All the products included in this aquarium kit work super efficiently in order to utilize power in the most effective way possible. The lights are bright, the filter is effective, the heater works consistently to keep the temperature stable and all of this happens at a low power consumption rate.

Features of Marineland (Aquaria) AMLPFK20B Biowheel Aquarium Kit

  1. Built-in LEDs in the hood
  2. Low-profile hood
  3. Comes with a filter and cartridges
  4. Comes with a heater
  5. Fish food and water conditioner samples included
  • Low energy consumption
  • Filter is quiet
  • LEDs are bright 
  • Heater works well
  • Easy to set up
  • Heavy and bulky

If you’re looking for a product that doesn’t drive up the electricity bill, this is it for you. It comes with all you need and it provides great value for money in the long-term.

cheap 20 gallon fish tank


Buyers’ Guide

What are some factors to consider when buying a 20 gallon fish tank? 

There are a number of things you need to decide and think about before you actually go out and buy a 20 gallon fish tank. Some of the things to keep in mind are:

  • Tank location in your home 

A 20 gallon fish tank is fairly large and you’re going to want to decide on where you’re going to put it in your home before you actually go out and buy one. 

The things to think about are whether the location is near an electrical socket, whether it’s away from direct sunlight or not and whether the surface it’s going to rest on going to be able to support the weight of the tank once it’s filled with water. 

The last point is especially important, if you plan on setting your fish tank on a table or counter-top, make sure that it’s able to handle the weight of the fish tank. If you have even a sliver of doubt about the surface’s capabilities, we suggest you invest in an aquarium stand. 

  • Be Wary of Cheap Deals 

The biggest and best brands in the aquarium business started with the aquarium kit trend a few years ago. Now, a lot of copycats are trying to cash in on this trend. When you go out to look for a cheap aquarium kit, you’re going to be bombarded with all kinds of deals such as aquariums that come with filters, heaters, air pumps, etc. While these deals may look appealing, we recommend you don’t buy into one without looking at reviews. More often than not, the extra equipment that comes with aquariums in these cheap deals is of sub-par quality and they stop working effectively after just a few weeks. 

  • Aesthetics and Look 

Lastly, you’re going to want to think about how the aquarium is going to look in your space. Fish are beautiful creatures and it’s important that the vessel they’re in be beautiful too. Try to imagine how the aquarium will look in its location in your home before you buy it. Make sure it compliments the color palette of your room and enhances the ambience rather than being an eye-sore. 

How do I set up my 20 gallon fish tank?

Setting up a 20 gallon fish tank can be tricky because of its size. Some easy steps you can follow for a successful setup are: 

  • Place the tank on its intended surface. Make sure it’s level and the surface is able to support the tank.
  • Mount all your external equipment on the tank such as heater, filter and air pump. 
  • Add cleaned gravel to your 20 gallon fish tank.
  • Add conditioned and dechlorinated water to the tank. 
  • Once you’ve added the water, observe the surface again and make sure it’s able to adequately support the weight of the 20 gallon fish tank now that it’s filled with water. 
  • Turn on all your equipment and let it run for 6-8 weeks without any fish. This process is known as cycling and is very important to do. If you want to add fish immediately, you can consider investing in biological supplements that help grow nitrifying bacteria immediately but we recommend that you do it naturally. 
  • Once cycling is complete, add your fish.

What equipment is absolutely essential for me to get for my 20 gallon fish tank?

The equipment you absolutely need for your 20 gallon fish tank is: 

  • Lighting 

Lighting is absolutely necessary for a number of reasons. 

Fish require light to be healthy and stimulated. Fish are happiest when you are able to simulate their natural environment and that includes having light that can mimic sunlight to an extent. We recommend getting LED lights as they are the best at replicating sunlight and are energy-efficient. African usually require about 12 hours of light every day while European fish require about 8 hours of light. 

You’ll also need lights for aesthetic purposes and to observe your fish. Fish have beautiful, brilliant, bright colors and you’re going to want to have a lighting system that is able to show these great colors in all their glory. 

  • Filter 

This is probably the most important piece of equipment that every aquarium needs to have. Fish require low levels of ammonia and clean water to be able to breathe properly. If you don’t have a filter, the water is going to deplete in oxygen levels very fast and this will lead to breathing and stress problems for your fish. 

Please get a filter that works effectively and does all three kinds of filtration i.e., chemical, biological and mechanical. 

  • Heater (if you have Tropical fish) 

If you’re running a coldwater fish tank, this piece of equipment is not needed. 

However, if you have tropical fish which require the water to be maintained at a certain temperature, you’re going to want to invest in a heater. 

Don’t go for a heater that doesn’t have a built-in thermostat. Go for one that is able to test the water temperature and turn off and on automatically so as to maintain the water temperature at an appropriate level. 

How many fish can I keep in my 20 gallon fish tank? 

That depends entirely on the type of fish you’re getting and how big they can grow up to be. 

As a general rule of thumb, you should have 1 inch of fish for every 1 gallon of water in your fish tank.

What are some water modifiers I should get for my 20 gallon fish tank?

Two things that are absolutely essential for modifying water is a dechlorinating agent and a water conditioner. 

A dechlorinating agent eliminates chlorine from the water. Chlorine is beneficial for us but very harmful to fish so it’s important that it’s eliminated from water before it’s used as tank water. 

A water conditioning agent helps detoxify water by neutralizing any toxins or harmful heavy metals it may have. 

Frequently Asked Questions

How do I control the algae in my 20 gallon fish tank? 

Algae is a pain to get rid of so it’s a good idea that you take measures beforehand to prevent it from ever breaking out in the first place. 

First thing you should do is make sure that your 20 gallon fish tank is not sitting in front of direct sunlight. Sunlight is not a factor you can control and too much of it can definitely cause an algae breakout. Having your fish tank near an open window or a door leading outside is a big no-no. 

Secondly, make sure your fish tank gets adequate light from your LED light source each day but be sure to turn it off so as not to be too excessive. Too much light can definitely cause algae to grow inside your fish tank. 

Perform regular pat-downs of the aquarium walls with a towel to prevent any build-up that may be occurring on them.

My 20 gallon fish tank is starting to smell. How do I fix this? 

A bad odor emanating from your fish tank could be due to a number of reasons such as a dead fish, uneaten excess food, or a dead plant or dead leaves.

The solution to this is definitely to look for the source of the odor. Look underneath the aquarium gravel, decorations and ornaments to ensure none of your fish have died and are rotting inside your tank. If you do happen to find one, remove it immediately. 

Observe the bottom of your fish tank and see if there’s any leftover food still hanging around at the bottom. If you do happen to spot some, remove it with the help of a fishnet. 

If a plant dies or its leaves break off, you can easily remove it with a fishnet too. 

If the problem persists, we recommend you do a deep clean of your fish tank with regular water changes.

My fish are swimming erratically in my 20 gallon fish tank. Why is this? 

This is usually due to too strong currents being created within the tank. 

Observe your filter or any air pump you may have installed on your 20 gallon fish tank. Monitor the currents they are creating and ensure they aren’t too strong for your fish. Smaller fish such as Bettas aren’t too strong swimmers and they would require a filter that doesn’t create too big waves inside the tank. 

If you do end up with equipment that is creating currents that are too strong, try modifying it so that it works at a slower pace. If this isn’t a possibility, change your equipment to one that operates at a lower capacity.

How do I maintain water clarity in my 20 gallon fish tank? 

You can easily maintain water clarity just by regular recommended practices that are suggested to every fish-keeper.

These include performing weekly 10-15% water changes, monitoring water parameters, cleaning the aquarium walls regularly, regularly cleaning your filter and regularly vacuuming aquarium gravel for dirt, debris and waste. 

How do I know that my 20 gallon fish tank has “cycled” completely?

Some ways to tell whether a tank has cycled completely are: 

  • Your fish have shown no signs of ammonia stress after two weeks of being added to your tank. 
  • Your ammonia and nitrite tests show results of 0 for at least eight consecutive days.

Final Verdict

20 gallon fish tanks are a very popular size among fish-keepers but it’s very hard to get a decent one at an affordable price. 

After rigorous testing, there’s no doubt in our minds that the product that provides the best value for money is the Marina LED Aquarium Kit. Its clean design and effective extra equipment it comes with make it the ultimate package for fish-keepers on a budget.

That brings us to the end of our post for cheap 20 gallon fish tanks. 

Let us know what tank you’re using for your little aquatic pets.

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