How Much Does a 20-gallon Aquarium Weigh?

Understanding the weight of a 20-gallon aquarium can help you make informed decisions when deciding where to place it.

Jun 22, 2025byDarren Ryding

how much does 20 gallon aquarium weigh

 

Many fish lovers underestimate the challenges of setting up a home aquarium. Perhaps one of the biggest challenges is where to put it. Its dimensions are just one aspect; you must also consider the weight of the tank once it’s filled with water. If the aquarium’s stand can’t bear its weight, it’s only a matter of time before disaster strikes.

 

In this guide, we’ll focus on everything you need to know about the weight of a 20-gallon aquarium, so you can make informed decisions when setting it up.

 

Many Factors Affect a 20-gallon Tank’s Exact Weight 

20 gallon aquarium
A standard 20-gallon fish tank. Image Credit: CBS.

 

Here are some considerations:

  • A full 20-gallon tank will weigh about 225 pounds (or 102 kg).
  • Most 20-gallon tanks have dimensions of either 24” x 12” x 16” or 30” x 12” x 12”.

 

The exact weight of an aquarium will depend on many factors. First, there’s the weight of the tank itself. Then, there’s the weight of water, which is approximately 8.34 pounds per gallon. The substrate is another variable, depending on whether you use gravel, sand, or coconut mulch. However, this won’t seriously impact the overall weight of the tank because these materials are so lightweight.

 

Accessories like filters, thermometers, and lighting systems are also important to consider. Meanwhile, the fish will also add extra weight to your home aquarium. This can vary significantly. For example, an Oscar can weigh up to 3.5 pounds, while a small goldfish may only be 0.6 pounds. Other animals, like turtles, can be much heavier, so this is something else to consider. Remember: fish, amphibians, and reptiles grow as they age. Choosing an adequately sized aquarium will avoid the problem of having pets outgrow their tank.

 

Aquariums Need a Steady, Solid Surface

fish tank plants
A fish tank with many plants. Image Credit: Wayfair.

 

There are many factors to consider when placing your aquarium. Choose a surface that’s strong and stable. Place the tank on a flat, even surface that can safely bear its weight.

 

You don’t want to choose a table with spindly legs. It’s better to place it on a sturdy area like a kitchen island or a lower table. Also, the floor underneath the tank should be level. There are also stands made specifically for bearing the weight of aquariums. Choose one made of a durable material, like metal. You can easily find these products online, however, they vary in quality, so check reviews and ratings first.

 

Be careful with wooden surfaces because they may warp over time, especially in areas with high humidity. We advise locating the tank away from windows; this doesn’t have much to do with weight, but algae blooms. Excessive light can feed microscopic organisms and cause your fish tank to become cloudy.

 

Notes When Choosing a Space for Your Aquarium

goldfish in tank
A goldfish in a tank. Image Credit: Shutterstock.

 

There are several safety issues to be mindful of when securing a 20-gallon tank. As you can imagine, 225 pounds is very heavy, and the tank can inflict significant damage if it falls. For reference, the average American man weighs 199.8 pounds. It’s easy to see how a tank of comparable weight could seriously injure someone if it fell on top of them. This is especially important for households with young children.

 

Take extra care when installing your aquarium if you have other pets like cats or dogs. These animals may accidentally knock over the tank by trying to snatch the fish or destabilize it when they run past. Tanks are expensive, and the shock of one shattering is also likely to kill your fish. It only takes a split second for something terrible to happen, so ensure that you place your 20-gallon tank in a safe location. It’s always better to prevent bad scenarios from occurring instead of dealing with them afterward.

 

Tips for Choosing the Right Tank Size

tropical fish tank
A tropical fish tank. Image Credit: Doha News.

 

We’ve focused on 20-gallon tanks in this guide because they are the most popular. However, you may choose another size depending on the fish you’re keeping. For example, angelfish and corydoras will need larger 55-gallon tanks. Other fish, like betta fish, can comfortably live in smaller aquariums.

 

To determine the weight of an aquarium, first consider the actual weight of the tank itself. For example, the leading 55-gallon tank on Amazon, which is primarily made of glass, weighs about 80 pounds. Water (which remember, is 8.34 pounds per gallon) alone would weigh 458.7 pounds. Add that to the weight of the tank, and you have a general estimate of how much it weighs.

 

Take the time to consider your fishes’ species, expectations, and time commitment when choosing an aquarium. A smaller tank doesn’t mean a smaller commitment—quite the opposite! At the same time, a larger aquarium could prove more of a hassle to clean if you’re only planning on doing it a few times a year. Research is key when determining which set-up is right for you (and your marine life!).

 

Wall-mounted 20-gallon Tanks: Considerations

luxurious wall mounted fish tank
A luxurious wall-mounted fish tank. Image Credit: YouTube.

 

Wall-mounted tanks have the benefit of saving floor space, and they’re becoming increasingly popular in recent years. Yet, weight is an important consideration before getting one. As noted, a 20-gallon wall-mounted tank would weigh more than 200 pounds, so make sure that your chosen wall and brackets can support that weight. Consult with a professional because the last thing you want is a shattered aquarium. There are many aquarists online who are eager to lend their insights!

 

 

 

Darren Ryding
byDarren Ryding

Darren is a passionate animal lover. He grew up on an organic vegetable farm with an ensemble of adopted animals including pygmy goats, pot-belly pigs, and donkeys. He currently lives with his Vietnamese rescue dog Bee.