HomeAquarium & Maintenance10 Gallon vs 20 Gallon Fish Tank Comparison: 4 Key Different

10 Gallon vs 20 Gallon Fish Tank Comparison: 4 Key Different

Both the 10 gallon tank and 20 gallon tank are popular among beginner fish enthusiasts. However, which one is better for you?

In this blog post, National Park Aquarium will compare the two options, highlighting their benefits and drawbacks in different circumstances. By the end of this post, you should have a clear idea of which size fish tank is right for you. 

Compare 10 Gallon vs. 20 Gallon Fish Tank

1. 10 Gallon vs 20 Gallon Fish Tank Dimensions

Volume Length x Width x Height
Gallon Litre Inch Centimetre
10 38 20″ x 10″ x 12″ 50 x 25 x 30cm
20 76 24″ x 12″ x 16″ 60 x 30 x 40cm
20 76 30″ x 12″ x 12″ 75 x 30 x 30cm

10 Gallon vs 20 Gallon Tank Dimensions in cm 

The first obvious difference between the 10-gallon fish tank and 20-gallon fish tank is size. 

  • There are two standard measurements for a 20-gallon tank. One measurement is 24 inches long, 12 inches wide, and 16 inches tall. Another one is 30 inches long, 12 inches wide, and 20 inches tall. 
  • There is only one standard 10 gallon tank size, which is 20 inches long, 10 inches wide, and 12 inches tall. 

2. 10 Gallon vs 20 Gallon Weight Comparison

Indeed, the 10-gallon tank dimensions will be more lightweight than the larger one with such measurements. However, it depends on the tank wall thickness and different brands that the weight can vary. 

  • When empty, an acrylic 10-gallon tank weighs around 10lbs, and a glass one measures around 13-15 lbs. 
  • When empty, an acrylic 20-gallon tank weighs around 20 lb, and a glass tank can be as heavy as 30 lbs and more. 

A 20-gallon tank dimensions can hold more water and thus more fish. If you are looking to add a lot of fish to your home, then the 20-gallon tank is the better option. 

Also, you should consider the available space in your house to see if it can fit which tank better. You do not want to cram a 20-inch aquarium inside a small living space.

10 gallon fish tank size comparison
10 gallon fish tank size comparison

3. Maintaining a 10-Gallon and a 20-Gallon Fish Tank

The complexity of maintaining a fish tank depends on the number and type of fish, as well as the aquarium setup. A 20-gallon tank may require more maintenance due to its larger size and potential for more fish.

Water quality is a crucial consideration when choosing a fish tank. Both the 10-gallon and 20-gallon tanks can maintain good water quality if properly maintained. 

To maintain water quality, a monthly 1/4 water change is necessary. Smaller tanks like the 10-gallon are generally easier to maintain in this regard.

Most fish thrive in a temperature range of 76°F – 80°F (24°C – 27°C). Insulating the tank or placing it near a heater is recommended, with smaller tanks being easier to warm up. However, for cold-water fish, either tank size is suitable. 

Fish require a constant oxygen supply, and oxygen filtration is essential. Larger tanks solve the issue of slower filtration in warmer water, making them advantageous. 

20 gallon fish tank size comparison
20 gallon fish tank size comparison

4. Cost and Ease of Cleaning

Cost is an important consideration when choosing a fish tank. A 10-gallon tank is generally cheaper due to its smaller size and reduced equipment requirements. 

Moreover, a smaller tank is easier and less expensive to clean and set up, making it the ideal choice for budget-conscious beginners. 

Considering ease of cleaning, the 10-gallon tank is preferable. However, if you plan to house a larger number of fish, the 20-gallon tank should be sufficient. 

Lean More: Best 10 Gallon Fish Tank (A Complete Beginner’s Guide)

What Fish Should You Keep in This Tank?

If you’re looking to stock a 10-gallon aquarium, you’ll need to be mindful of the size of the tank. Most fish require a larger minimum tank size, so you’ll have to choose small fish that don’t require much space. Fortunately, there are many options to stocking a 10-gallon tank.

Some of the best fish for a 10-gallon tank include Betta, Guppy, Rice Fish, Chili Rasbora, White Cloud Minnow, Celestial Pearl Danio, Neon Tetra, Zebra Danio, Dwarf Gourami and more!

A 20-gallon aquarium provides more options than a 10-gallon aquarium due to its larger volume of water. This makes it suitable for a variety of different fish, giving you more options to choose from.

Some of the best fish for a 20-gallon aquarium include Guppies, Neon Tetras, Platies Fish, Corydoras Catfish, Dwarf Gouramis, Mollies, Zebra Danios, GloFish and more!

The Pros and Cons of 10 vs 20 Gallon Tank Size

As with anything, both 10 and 20 gallon tanks have their own sets of pros and cons.

10 Gallon Tank

  • Compact size: Ideal for small spaces.
  • Low maintenance: Fewer fish mean less cleaning.
  • Lower startup cost: Less equipment and fewer fish to buy.
  • Limited space: Fewer fish and decoration options.
  • Less stable: Smaller volume of water can fluctuate quickly in temperature and chemical balance.
  • More design opportunities: Greater scope for plant and decoration variety.

20 Gallon Tank

  • More room: You can keep more or larger fish.
  • More stable: Larger volume of water maintains temperature and balance more easily.
  • More design opportunities: Greater scope for plant and decoration variety.
  • Needs more space: Not as suitable for small apartments.
  • More maintenance: More fish produce more waste.
  • Higher startup cost: More equipment and fish to purchase initially.


When choosing a fish tank, it’s important to consider the size of the tank, the type of fish you want to keep, and your budget. Between the 10 gallon vs 20 gallon fish tank dimensions, each type works better for different living spaces, expenses, and maintenance effort. However, a beginner should start with the smaller tank since there will be fewer problems and less cost to worry about.

Which one should you buy? Well, the answer depends on your needs.


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Further Reading
Kevin Mills, the founder of Nationalparkaquarium.org


-- Founder --

I'm Kevin Mills, the founder of Nationalparkaquarium.org, where I share my deep passion for aquariums and aquatic life. With over 20 years of experience in fishkeeping, covering everything from tending to saltwater and freshwater tanks.

Kathleen Wood


-- Interrogator --

Kathleen Wood, a seasoned marine biologist, possesses a wealth of knowledge and experience in her field. Her research on tropical fish biodiversity spans over three decades, and she has contributed numerous scientific papers on aquatic life.