What Size Fish Tank Should I Get? (The Ideal Sizes)

what size fish tank should i get

Folks pondering about venturing into aquarium hobby often ask, what size fish tank should I get? Although you can get a 2-gallon nano tank or a monstrous 10,000-gallon aquarium, the choice depends on your fish, stocking size, budget, aquarium setup, and other considerations. Join us in this article to determine the best aquarium size for yourneedsHow Big of a Fish Tank Should I Get?

The best fish tank size is relative. Different folks vary in aquarium hobby needs. Some prefer a tropical freshwater setup, while others adore the vibrant views of a marine (saltwater) ecosystem.

So, let us look at the different aquarium fish tank sizes available.

The Ideal Fish Tank Size for Your Needs

1. Below 10 gallons


Many parents gift their kids a 5 gallon aquarium to kick-start their journey into hobby fish keeping. These small-sized fish tanks look neat on a coffee table or a child’s study desk. They are also ideal for homes with limited space to spare.

Sadly, small fish tanks do not offer enough room for fish to roam and be happy. Even solitary fish deserve an environment that allows them to be free from stress. Otherwise, they become more vulnerable to illnesses.

Another issue with small fish tanks for beginners is the water quality can be challenging to control. The small volume means the water can easily build up with fish waste and other organics, causing pH and water parameter fluctuations.

To circumvent the issue, opt for aquatic creatures that can do well in a nano tank, like kuhli loach, panda guppy, or chili rasboras. Alternatively, you can just set up an aquatic aquarium landscape with aquatic plants, such as java fern, rotala rotundifolia, Amazon sword, or marimo moss balls.


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  • Budget-friendly
  • Space-saver
  • Ideal for aquatic plants



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  • Water quality parameters are challenging to control
  • Stressful to fish


2. Between 11 and 20 gallons


These fish tanks might be bigger than 10-gallon units, but they are relatively affordable and don’t require too much space. You can also put more fish and accessories, following the one-inch-one-gallon rule.

Although these aquariums are more spacious than small tanks, they still demand vigilant water parameter monitoring. Water management is easy if you include a good-quality fish tank filtration system in these aquariums.

Still, a 20 gallon aquarium can be an excellent small fish tank idea if you want to give one to your kid to put in their bedroom.


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  • Affordable
  • Requires minimal space
  • Suitable as a decorative piece



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  • Vigilant maintenance required


3. Between 21 and 40 gallons


Of the different sizes of fish tanks, most homes find 21 to 40 gallons the ideal range. These units are within the budgets of most families, and their volumes allow for better control of water parameter fluctuations.

A more forgiving maintenance requirement is not the only positive about a 40 gallon fish tank. You canbuild and customize a community of different fish species, add vibrant aquatic plants, or keep several large fish without worrying about their happiness and health.

For example, you can put three fancy goldfish in an aquarium with 40 gallons of water.

The only downside to these tank sizes is their higher price and ample space requirement.


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  • Less challenging to maintain
  • Allows for more fish to keep
  • Additional personalization
  • The fish tank becomes a centerpiece



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  • A bit pricey
  • Requires considerable space


4. Above 40 gallons


Large aquarium sizes are the best for fish and other aquatic life forms. However, they are not for everyone.

Not only are these heavy, but they can be pricey, too. Aquariums with capacities exceeding 90 gallons can be challenging to maintain. They also demand custom-built aquarium stands because ordinary household furniture might buckle under the weight. Space can also be an issue.

On the bright side, a 55 gallon fish tank will have you the talk of the town. These monstrous aquariums are perfect for showcasing different fish species in a near-identical habitat without stressing them out.


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  • Excellent centerpieces
  • Do not stress fish
  • Can accommodate diverse aquatic life forms



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  • Pricey, heavy, and not space-efficient
  • Requires special stands
  • Challenging to clean and maintain


When it Comes to Aquariums, Bigger is Better!


If you must choose between a 30-gallon and a 50-gallon fish tank, we would suggest picking the latter. Here are the advantages of owning a larger-sized fish tank.

1. Happier and healthier fish

Small-sized aquariums make it hard to provide fish the space to explore and be happy. In small enclosures, fish will experience stress, which makes them more vulnerable to diseases and illnesses.

A large tank not only guarantees fish happiness. It also safeguards them. So, how big should a fish tank be? We recommend buying the largest aquarium possible.

2. Easier to maintain the ideal water parameters

Water temperature and chemistry are two parameters you will not have any issues controlling in a large fish tank.

Large-sized tanks are more effortless to keep the water parameters stable because the large water volume dilutes organic matter. Nitrates, nitrites, and phosphates will not spike as drastically as in small tanks.

Fish Tank Size for Beginners


The minimum recommended size of a beginner fish tank is 5 to 20 gallons.

However, as mentioned in the preceding section, a bigger fish tank is better. The only issue you might encounter is the price. Your kid or beginner aquarist can put more fish into the tank without worrying about water quality tolerances.

A large tank allows beginners to learn to control various water parameters while ensuring happy fish. Water changes are also more straightforward with larger-sized tanks than with tinier versions.

Things to Consider before Choosing a Suitable Fish Tank Size

The common fish tank sizes range from 2.5 to 180 gallons. Their sizes in litres are 10 (9.46 liters) to 680 (681.37 liters). So, which aquarium should you pick? Please consider the following.

Types and Size of Fish


The current guideline dictates reserving a gallon of fish tank for every inch of fish. The issue with this “rule” is it neglects water surface area, which is necessary to ensure effective carbon dioxide-oxygen gas exchange.

It also does not consider tank decorations, waste generation, fish activity levels, maximum fish growth, fish aggression, aquarium environmental requirements, and fish body shape.

Hence, a modified “rule” states that a single fish should have at least five gallons of aquatic real estate.

We also recommend researching the fish you want to keep, including their behavior and water tolerances.

Fish Tank Weight

One of the most often overlooked fish tank measurements is weight. Water tips the scale at 8.34 pounds (or 3.78 kg) for every gallon.

Hence, a 30-gallon aquarium can weigh at least 250.2 pounds (30×8.34), and we did not include the fish tank’s empty weight yet. The average 30-gallon tank weighs 48 pounds, raising our total to less than 300 pounds.

Aquarium weight is crucial because you want a sturdy, reliable, and stable fish tank stand.

You can look at the following size chart to know how heavy fish tanks can be. This table also includes the aquarium sizes and dimensions, so you won’t have to use a calculator to estimate their measurements.

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Fish Tank Size (in Gallons)L × W × H
(in inches)
Gross Weight (including substrate, water, fish, accessories; in pounds)Gross Weight (in kg)
0.5 to 10.016″ x 8″ x 10″ to
20″ x 10″ x 12″
4.17 to 83.41.89 to 37.83
10.0 to 20.020″ x 10″ x 12″
24″ x 12″ x 16″
83.4 to 166.837.83 to 75.66
20.0 to 40.024″ x 12″ x 16″
48″ x 12″ x 16″
166.8 to 333.675.66 to 151.32
40.0 to 60.048″ x 12″ x 16″
50” x 14.25” x 28”
333.6 to 500.4151.32 to 226.98
60.0 to 90.048.5” x 12.75” x 25”
48″ x 18″ x 24″
500.4 to 750.6226.98 to 340.47
>90.048″ x 18″ x 24″ and above>750.6>340.47


Types of Fish Tank


Fish tanks come in various types, including the following.

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  • Freshwater – Easy to maintain and more affordable than saltwater aquariums. They are perfect for newbie aquarists.
  • Saltwater – Pricey and challenging to maintain, saltwater aquariums are large because they require more gadgets, accessories, and unique living organisms. Typically, even beginner saltwater tanks are recommended to be 55 to 75 gallons, whereas more seasoned fish keepers tend to prefer at least 100 gallons.
  • Fish Bowl – Simple and classic, the fish bowl is perfect for youngsters who only want one or two small fish.
  • Fish Tank or Aquarium – Featuring acrylic or glass, fish tanks are transparent, allowing you to see through their panels.


Problems of Using Smaller Tanks

Fish tanks too small for fish and other aquatic livestock can pose several concerns, including the following.

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  • Fish do not reach their maximum growth potenal
  • Fish can develop fatty liver disease secondary to stunted growth
  • Increased risk of fish aggression because of competition for space
  • Uncontrolled nitrate, nitrite, and phosphate spikes lead to poor water quality parameters and undermine fish safety and health
  • Insufficient oxygen dissolved in the water
  • Chronic stress in fish, which leads to disease, appetite loss, and poor scale and skin quality



We cannot give you a definitive answer to your question, what size fish tank should I get? However, we can tell you to pick the largest aquarium your budget and home can accommodate. This approach will give you more leeway in fish choices, aquarium setups, and tank maintenance.

Beginners can always opt for 20 gallons as a starting fish tank size, although the bigger, the better. An intelligent decision is a cinch to come by with all the information we just shared