20 Gallon Fish Tank: Which one Best for my Fish? 2020


20-gallon fish tanks are ideal for beginners and anyone who’s on a budget. They’re more spacious than 10-gallon tanks and open you up to a wide variety of fish and plant species.


At this size, a 20-gallon tank isn’t so large that it racks up high maintenance costs, and it’s got just the right amount of water to maintain constant temperatures.


Here’s what you should know about setting up a 20-gallon fish tank.


But First: How Much Does a 20Gallon Fish Tank Weigh?


20 gallon fish tank


Before bringing a 20-gallon tank into your home, you should be aware of how much it will weigh.


For obvious reasons, an empty fish tank is going to weigh just a few pounds, but when you fill it with water, it will easily go up to several hundreds of pounds.


The first thing to start with is the dimensions of the fish tank. It’s measured by L (length), W (width), and H (height).


A standard 20-gallon tank will measure anywhere from 24 inches by 12 inches by 16 inches. This means that the total weight will increase all the way up to 225 lbs.


For obvious reasons, it’s not going to be easy moving this mammoth of a tank around your house and you should decide on the ideal location beforehand.


Another thing to keep in mind is the fish stand.


It is recommended to buy a specially designed 20-gallon tank fish stand instead of placing your aquarium over a makeshift dresser.


A dresser will buckle under the weight of a fully equipped fish tank, especially one that weighs well over 200 pounds.


Which 20 Gallon Fish Tank Should I Buy?


There are many sizes, shapes, and types of 20-gallon fish tanks out there. Some of these may come included with fish tank starter kits, while others will be empty so you’ll have to buy your equipment.


We recommend buying your equipment anyways and not trust the quality supplied by your manufacturer (they usually cut corners to save costs).


Below is our pick of the best 20-gallon fish tanks.


1. 20 Gallon Aquarium Kit by the Tetra Store


fish tank



This tank is ideal for new fishkeepers who don’t have a clue about fishkeeping. It comes with a fully fleshed out starter’s kit that includes a hood, integrated light, a filter, and a heater.


More importantly, it also comes with four artificial plants that serve as an excellent tutorial before you can introduce live plants.


Setting up this 20 gallon fish tank is insanely straightforward, simply add the substrate and your fish stock, and that’s all folks!


There’s another reason why this tank made it to our list: the lifetime warranty.


The lifetime warranty means that your investment is safe and sound.


The dimensions for this aquarium is as follows: 24” by 12” by 16”




  • Scratch-resistant glass
  • Lifetime warranty
  • Starter kit includes everything you could ever need
  • The filter is quiet and gets the job done
  • Hinged hood makes it easy to clean the tank




  • The plants look obviously fake
  • The lights may be too inadequate for certain fish species


All in all, this aquarium is a sound investment. If you can’t find this model on Amazon, try searching on Etsy and Walmart.

Check out prices and availability on Amazon ( Click here to check )


2. Marina LED Aquarium Kit


fish tank


The manufacturer went for a simple, minimalistic design. This Marina Aquarium features a standard rectangular shape, making it great for beginners in home and office environments.


Moreover, the tank easily blends into the office décor so that it doesn’t stick out like a sore thumb. Its kit features stunning light fixtures that would make the fish feel right at home. A bonus feature of the light fixtures is that they can add more color to your room.


The LED light doesn’t disrupt the fish’s normal life and is incredibly energy efficient, saving you energy bills in the long run. This tank comes with the required filters that can be installed with the help of a simple clip-on filter. What we especially liked about the tank is the ability to swap out the filter cartridges with ease.


You can replace them with a few simple steps whenever maintenance is due. The filter aids in the removal of toxic pollutants and bioload, such as ammonia, leaving your tank with clean best water that will keep your fish happy for years to come.


Click here to check prices and availability on Amazon.


3. Half Moon Shaped Aquarium by Marineland (AML11536)


This aquarium features a stunning half-moon shape that will spruce up your interior décor. The kit comes with all the necessary equipment you could ever need, including LED light fixtures and a clear plastic canopy with small cutouts for feeding.


The canopy makes it easy (and quick) to feed your fish. Furthermore, the canopy minimizes water evaporation from the tank, reducing the need to constantly refill the water to maintain its level. It’s super easy to install the filter in its position.


Note: The filter is not included with this model, but you can easily find one and mount one in the provided cutouts.


This review would be incomplete without mentioning the half-moon shape. Many fishkeepers will enjoy the view which is only possible with this kind of design. The LED lighting and the unique view make for a stunning combination that is addicting to view.


The LED lights deserve special mention here. The kit comes with 3 blue LED lights and 42 white LED lights. You can control the color depending on the type of day. When installed in their correct positions, the LEDs create a shimmering effect that mimics the underwater effect of sunlight.


The nighttime LEDs mimic the fish’s biological clock, signaling them that its time to sleep (or start hunting, depending on the species).


Click here to check prices and availability on Amazon.


Best Fish for a 20 Gallon Fish Tank


What fish are best for a 20-gallon fish tank? Below is our list of some cool fish for a 20-gallon tank. Of course, there are several more species that you can choose from, the ones highlighted below are the ideal choice for beginners.



Adding Tank Mates in a 20 Gallon Aquarium


adding tank mates


Most fishkeepers want to build a thriving community aquarium, a tank where multiple species and ecosystems can live together with peace.


But there are a few things to keep in mind before adding tank mates, these include:


Water parameters: Only select tank mates that share the same water parameters, including temperature and hardness levels.


Aggression Levels: Adding aggressive species to a small 20-gallon tank is not advisable since they’ll give their tank mates a hard time. If you do decide to add aggressive fish, make sure they’re the only specimen in the tank.


Schooling Fish: If you want your fish to live in a group, try to create schools of 6 or more. This will make them feel secure and happy in their new habitat.


Territories: Most fish species will carve out a small place in the tank and call it their home. Any fish that dare to swim closer will be given a hard time.


Make sure to give these territorial enough room in the tank. They will become too aggressive for their good in an overly populated tank.


Tank Columns: Not all species occupy the same column of the tank. Some species are top, bottom, and mid-water dwellers. Choose a combination of fish that occupy different column levels.


This way, they can be spread out over the aquarium instead of crowing into a single space.


Finding the Right Equipment for the Tank


finding right equipment


Earlier in the blog, we asked you to not depend on the tank’s built-in equipment – they’re mostly low quality and will eventually give out. Therefore, it is best to invest in quality equipment that you can install in your tank.


You have to create a perfect, healthy environment for your fish. This includes the right lighting to help them thrive and grow.


They need the right substrate, temperature, plants, and decorations to hide and swim and stay healthy. More importantly, fish need purified water with the right pH, and beneficial bacteria colonies to keep the tank clean.


Let’s get down to brass tacks.


20 Gallon Tank Filter


A filter is the most basic piece of equipment in a 20-gallon tank that you should never skimp out on.


It provides your fish with clean and clear water. A low quality, cheap filter doesn’t do a great job and will fail much sooner than a higher quality product.


So investing in a good product from the get-go is a smart decision that saves you money in the long run.


As a general rule of thumb, your choice of filter should easily filter through all of the water in the tank at least 3 to 4 times in an hour. A 20-gallon tank,


for example, will need a filter with a flow rate of 80 gallons per hour (or GPH).  If you ask us, however,


it’s better to invest in a tank with a GPH that will filter the water 9 to 10 times an hour. More is better.


Types of filters you can see buying for your 20 gallon fish tank:


Internal filters: These filters are installed on the inside of the tank. It is easy to install internal filters and maintenance is also fairly simple. They are also very quiet (since they’re inside the tank).


Sponge filters: These filters are installed inside the tank. Their working mechanism is rather creative. They force water through the large surface area of the sponge with the help of an air pump or a powerhead.  This allows them to act as a highly efficient filter (both bio and mechanical) that keeps the tank clean round the clock.


Hang-on-the-back: This common tank hangs on the back of the tank. They’re not as bulky as canister filters and can’t sustain larger aquariums. More importantly, HOB filters are more budget-friendly and therefore, ideal for your average aquarium enthusiast.


Ideal Water Flow for Fish and Plant


Some fish prefer low to modest water movement like the Dwarf Gouramis, others don’t like any water movement at all. Fish species like the Zebra Danios require high water currents round the clock.


Before adding water movement to your tank, make sure that all your fish stock will be comfortable with water currents.


Finding the Ideal 20 Gallon Tank Heater


There are two things you should consider before choosing a heater for your 20-gallon tank: the ambient temperature of the room of the heater’s quality.


The capacity of the heater should be selected based on the ambient temperature of the room. If your area has a warmer climate, your heater should be able to increase the temperature by 9 degrees or less. In this case, choose a heater with a capacity for about 100 watts.


If the ambient temperature drops below 65 degrees or more, then the heater should have a capacity of about 200 watts to maintain a constant temperature.


When it comes to heaters, you get what you pay for. They easily run into various maintenance issues, such as refusing to function after a few weeks of use, getting stuck, and even frying your fish! If you’re not careful, this may happen.


A cheap heater may seem cheap in the short run, but if you’re forced to buy a new one, or have to replace all your fish stock in the tank, all of a sudden that cheap price doesn’t seem like an advantage.


A high-quality heater should have the following features:


  • A temperature dial to make it easier to control the temperature
  • Safety shut off sensor to shut the heater when the temperature gets out of control
  • Indicator light to help you know when the device is functioning


Submersible Heater best budget aquarium heater that will last you a long while, choose from a range of options including 50 watts, 100 watts, 150 watts, and even 300 watts.  


Grave Vacuum


This piece of equipment is a lifesaver when it comes to tank maintenance. The gravel vacuum lets you remove water, fish waste, and other dirt out of the tank (and substrate).




You will have to clean algae that grow on the inside walls of your tank. For this purpose, you can buy generic sponges at your local grocery store. Just make sure they don’t come with any soap or chemicals.




This is important if your source of water comes from the tap. Simply put, a de-chlorinator is a chemical additive that renders chlorine in your water harmless to your fish and bacteria.




Nets are useful if you need to add, catch, or move fish from one tank to another. It also comes in handy when you have to remove dead fish – that is a frequent occurrence in most tanks.




A lid can be necessary if your fish are jumpers and can escape. They also keep dust and bugs out and minimize the evaporation of water.


Test Kit


This is absolutely essential if you want to test your water regularly, especially when you’re cycling your tank. It is of paramount importance to the water’s quality so you can improve it for the better. We recommend going with liquid water test kit because they’re reliable and last longer than strips.


Setting Up a 20Gallon Fish Tank


setting up 20 gallon fish


  1. Place the tank on level ground. Make sure the entire base tank is supported otherwise it could develop leaks.
  2. Rinse the substrate and gently place it in the bottom of the tank. Create a nice 1” layer of the substrate.
  3. Install your devices in the tank, including the filter, heater, air pump, etc. Leave them unplugged for now.
  4. Add your décor, including rockwork, caves, and live plants.
  5. Fill the tank with water. Make sure to pour it slowly so as not to disrupt the substrate. Once you’ve added half the tank with water, time to add the live plants into the substrate.
  6. Use a de-chlorinator and start your devices.
  7. Place your lid and light fixtures in the tank.
  8. Cycle the 20-gallon tank, learn how to do it here.
  9. Add your fish to the 20-gallon fish tank.
  10. Stay on top of regular tank husbandry to keep everything running like clockwork.

Wrapping Up


A few key takeaways from this blog that we wanted to touch on:


Your tank needs regular maintenance. For example, when it comes to the water, it’s out with the old, in with the new. Your live plants will have to be pruned, the algae wiped clean off the tank, and you must remove the buildup of ammonia.


The more fish you add to the tank, the more you’ll have to maintain it.


And as always, research your fish species before you add them to your tank. You have an ethical responsibility to your fish –and they’re not just a source of entertainment.


We hope you enjoy this process. Setting up a new tank feels like a journey with infinite possibilities. You’re creating a literal work of art where your little fish buddies can hang out in peace.

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