Dimensions Of A Standard 20 Gallon Fish Tank: Aquarium Guide

If it’s your first time trying to get a fish tank, and you are being asked if you want a 20-gallon fish tank, the first question you would probably ask yourself is “how big is a 20 gallon tank?” or “how big is a 20 gallon aquarium?”

Depending on what you’ve envisioned, a 20-gallon aquarium could be the perfect size you’re looking for, especially if you are a beginner aquarist. 

It is large enough to keep a variety of fish. A 20-gallon tank could also be the right size you need if you plan to keep small fish that are about 2 to 4 inches long. This is one reason why it makes more sense to choose the kind of fish you want to have before deciding on a tank size. The fish actually determine how big the aquarium would be. 

As for a 20-gallon fish tank, the dimension is 24″ x 12″ x 16″ (when it’s 20-gallon high) and 30″ x 12″ x 12″ (when it’s 20-gallon long).

How much weight does a 20 gallon fish tank hold?

If the fish tank is empty, it would way around 25 lbs. When it’s filled with water and fish, it weighs 225 lbs. This weight doesn’t change regardless of the shape of the tank. All 20-gallon tanks shaped square, Pentagon, hexagon, or even cylinder have the same weight.

But occasionally, the tank can be slightly heavier or lighter depending on how thick the glass is.  

Size and shape of a fish tank

There are different sizes and shapes of aquariums. It all depends on the amount of space you have created in your home for the tank. Some folks go ahead to buy a 50-gallon tank because they have enough space to accommodate it, while some people choose to settle for a 10-gallon fish tank because their sitting room or bedroom isn’t big enough to house a large one. 

The most common fish tank type, whether 20 gallons or not, is rectangular. This shape allows the fish to swim comfortably and move freely within the aquarium. Mind you, there are numerous shapes and sizes of fish tanks in the market.

Although rectangular is quite common, you can find hexagons and cylinders. Besides, there are custom-made tanks. You can hire professional aquarium builders to customize a special tank that fits in your home. However, custom-made fish tanks often cost money. 

5 Gallon vs 10 Gallon vs 20 Gallon Fish Tank

There are 2 more fish tanks smaller than a 20-gallon aquarium of which a 5 gallon fish tank is the smallest. Having taken certain factors into consideration, here is a table explaining the difference between these 3 fish tanks. 

Features	5 Gallon Fish Tank	10 Gallon Fish Tank	20 Gallon Fish Tank
Size and weight	Smaller	Bigger	Biggest
Fish quantity	4 – 6	8 – 10	10 – 20
Maintenance difficultly	Easier	Harder	Difficult
Price	Cheap	Pricey	Most expensive

Does a 20 gallon fish tank need a mat?

Your 20-gallon fish tank needs a mat if it’s rimless. Braced tanks don’t really need mats. Here’s what you should keep in mind. Fish tanks are quite heavy when they get full. It doesn’t matter if it’s a 20-gallon or a 40-gallon tank.

Mind you, the doesn’t contain only water. There’s sand, decors, filter, light, and other accessories that improve the functionality of the tank.

All these things will make the aquarium much heavier. If the surface where the tank sits is leveled, the weight won’t be a problem. If the surface is not completely leveled, there’s a very high chance the tank gets cracked. 

How many fish can a 20 gallon fish tank accommodate?

There’s a simple rule you can follow to do this right: one gallon for an inch of every fish you want to put into the tank. To determine the number of fish that can be accommodated in your tank, you need to first decide on the species of fish you want to keep.

Also, bear in mind that some species of fish may look small but they need more space to thrive in the aquarium. So, you can’t just dump so many fish in one tank because they are small. It does not work that way.

A lot of fish need a spacious environment to live happily. When choosing a fish, make sure you do some research to find out how much space it needs. 

How to set up a 20 gallon fish tank

Setting up an aquarium in your living space can be a delicate process. If you aren’t careful, you could seriously damage your tank. Here are some helpful steps you can follow to set up a 20-gallon fish tank:

• The first thing you do is place your tank on a flat surface. You can use a mat to be on the safe side. 
• Make sure you clean out the substrate carefully. Doing this is important in order to remove dirt which can ruin the water in the aquarium. 
• After cleaning the substrate, gently put it back inside the tank. 
• The next step is to place all the tank equipment where they are supposed to be. But don’t plug it in yet. Also, make sure none of the equipment touches water. 
• Gently fill in water. Make sure you do this slowly. If you fill the water too fast, the force would create a hole in the substrate. 
• Having filled the tank halfway, add the live plants, and then fill it up with water. 
• Plug in the equipment and place the lid and plug in the lights. It will begin to circle at this point.  

It’s not compulsory you set up your aquarium on your own. If you don’t want to damage your tank in the process, then maybe you should leave it to the pros.

Usually, when you get a custom-made fish tank, the company that built it would be responsible for installing it. They can also offer to carry out some maintenance duties for a reasonable fee. You don’t have to lift a finger.

However, in a situation where you didn’t pay for a custom-made aquarium, you can hire an expert separately to install the tank in your home.  

Choosing Your Filter For Your 20 Gallon Tank

Every tank has a filtration system. That’s how you keep the water clean and make the fish comfortable. Don’t just pick a random filter for your aquarium. The filter you choose must be compatible with the fish tank.

When using a 20-gallon tank, you shouldn’t use a filter that is meant for a 10 or 15-gallon tank. The filter would be too small for the tank, and that would certainly affect its efficiency. You need to get the right filter that fits the size of your tank and in case your filter is faulty you can check out how to fix a top fin filter.  

FAQs

Final thoughts on a standard 20 gallon fish tank

Beginner aquarists don’t have to bother themselves with getting a very large tank. It’s important to start with something you can handle. Besides, there are several species of fish you can keep in your aquarium. But when choosing fish, go for the ones that are not too demanding in terms of maintenance and upkeep. Otherwise, you won’t be able to look after the fish in the long term.