What Size Aquarium Should a Beginner Buy?

Choosing the right aquarium size is one of the most important decisions when setting up your first fish tank.

A very small aquarium may look easier and cheaper to manage, but smaller volumes of water can change more quickly. Temperature, waste levels and other water conditions can become unstable faster than they would in a larger tank.

For many beginners, choosing a slightly larger aquarium can make fishkeeping easier and give you more options when selecting suitable fish.

If you are still planning your first setup, start with our beginner guide to setting up your first aquarium and freshwater aquarium equipment checklist.

What Is a Good Aquarium Size for a Beginner?

There is no single perfect aquarium size for every beginner because the correct tank depends on the fish you want to keep, the space available and the type of aquarium you are planning.

As a practical starting point, an aquarium around 50–60 litres or larger is often easier for a beginner to manage than a very small tank.

RSPCA Australia recommends a minimum tank volume of 50 litres for tropical fish and notes that the adult size and total number of fish need to be considered when choosing an aquarium. Larger tanks and filters generally provide more flexibility.

That does not mean every 50-litre aquarium is suitable for every fish. Some species require considerably more swimming space, while others have territorial or social requirements that influence the tank size needed.

Why Can Small Aquariums Be Harder to Manage?

A small aquarium contains less water, so changes can happen more quickly.

For example:

• Waste can build up faster.
• Temperature can change more quickly.
• Evaporation has a greater effect on water volume.
• Overfeeding can have a larger impact.
• There is less room for fish to establish territories.
• Stocking options are more limited.

Water quality is one of the most important parts of fish health, and effective biological filtration is essential in a new aquarium. :chatgpt-content-reference{index="1"}

A larger water volume does not remove the need for testing and maintenance, but it can provide more stability when something changes.

Should a Beginner Avoid Nano Aquariums?

Not necessarily.

A nano aquarium can be a great choice when it is planned around livestock that genuinely suit a small tank.

The important thing is not to assume that a small aquarium means less work.

Nano tanks often require careful stocking, regular maintenance and close attention to water quality because there is less room for error.

They can work very well for:

• Small planted aquariums.
• Suitable shrimp setups.
• Species that genuinely suit smaller aquariums.
• Aquascapes where livestock requirements are carefully considered.

They are less suitable when someone buys a small tank first and then tries to fit unsuitable fish into it later.

How Much Does Aquarium Size Really Matter?

Aquarium size affects much more than how much water the tank holds.

It influences:

• Which fish species can be kept.
• How many fish the aquarium can support.
• Swimming space.
• Territory and hiding areas.
• Filter options.
• Heater requirements.
• Maintenance workload.
• The amount of substrate and hardscape required.
• The total weight of the setup.

Choose the Fish Before You Choose the Tank

One of the best ways to avoid buying the wrong aquarium is to decide what kind of fish you would like to keep first.

When researching fish, check:

• Adult size.
• Minimum aquarium size.
• Swimming behaviour.
• Whether the species should be kept alone, in pairs or in groups.
• Temperament and territorial behaviour.
• Temperature requirements.
• Water chemistry preferences.

Merck Veterinary Manual also notes that different fish species can have very different behavioural, environmental and space requirements, so tank size should be matched to the livestock rather than chosen in isolation. :chatgpt-content-reference{index="2"}

Browse our freshwater aquarium fish range and check the care information for the species you are considering before deciding on the tank.

Common Aquarium Sizes for Beginners

Aquarium dimensions vary between manufacturers, so litres alone do not tell you everything. Tank length and floor area can be just as important as total volume.

Under 40 Litres

Very small aquariums can be attractive and space-efficient, but they offer limited stocking options and can require close attention to maintenance.

These tanks are best chosen for livestock that genuinely suit the available space rather than treated as a general-purpose community aquarium.

Around 50–70 Litres

This size range can be a practical starting point for beginners who have limited space but still want enough water volume for a more manageable freshwater setup.

It can suit selected small community fish or planted aquariums when stocking is appropriate.

Around 80–120 Litres

This is a very useful size range for beginners because it gives more room for fish selection, aquascaping and filtration.

The larger water volume can also make the aquarium more forgiving than a nano setup.

Around 150–250 Litres

Larger aquariums open up more stocking options and provide more swimming space, but they also require a stronger stand, larger filter, more substrate and more water during maintenance.

They can still be excellent beginner aquariums when the available space and budget suit the setup.

Does Tank Length Matter?

Yes.

Two aquariums can contain a similar volume of water but have very different shapes.

A longer aquarium may provide more horizontal swimming space than a tall, narrow aquarium of similar volume.

This can matter for active schooling fish and species that spend much of their time swimming horizontally.

Bottom-dwelling fish may also benefit from a larger footprint rather than simply more height.

What About 2ft, 3ft and 4ft Aquariums?

Aquarium length is another common way Australian fishkeepers describe tanks.

2ft Aquariums

A 2ft aquarium can suit many beginner setups, but actual volume varies depending on the tank's width and height.

Always check the litre capacity as well as the external dimensions.

3ft Aquariums

A 3ft aquarium provides more swimming space and generally gives you more flexibility when planning a community tank.

4ft Aquariums

A 4ft aquarium offers substantially more room for suitable larger fish, larger groups and more complex aquascaping.

The increased size also means you need to think carefully about stand strength, filtration and the weight of the completed aquarium.

How Heavy Is a Filled Aquarium?

Aquariums become much heavier than many new fishkeepers expect.

One litre of freshwater weighs approximately one kilogram, before including:

• The glass aquarium.
• The cabinet or stand.
• Substrate.
• Rocks.
• Driftwood.
• Filters and equipment.

Merck also notes that even relatively small aquariums can become extremely heavy once filled. :chatgpt-content-reference{index="3"}

Use a properly supported, level surface designed for the size and weight of the aquarium.

How Much Space Should I Leave Around the Aquarium?

Do not choose a tank that only just fits into the available space.

Allow room for:

• Filter hoses or equipment.
• Power cables.
• Opening lids.
• Feeding.
• Water changes.
• Cleaning the glass.
• Accessing the filter for maintenance.

Also avoid placing the aquarium where it receives prolonged direct sunlight. Direct sunlight can encourage algae growth and may contribute to unwanted temperature increases. :chatgpt-content-reference{index="4"}

Does a Bigger Aquarium Need More Maintenance?

A larger aquarium involves more water during water changes and generally uses larger equipment.

However, that does not necessarily mean it is harder to keep successfully.

Larger aquariums often provide:

• More stable water volume.
• More room for suitable filtration.
• Greater stocking flexibility.
• More room for aquascaping and territories.

A well-planned larger aquarium can therefore be easier for a beginner than an overcrowded small aquarium.

Don't Use the "One Inch Per Gallon" Rule

Older aquarium advice sometimes suggests allowing a fixed amount of water for every centimetre or inch of fish.

This is too simplistic to use as a reliable stocking method.

A 10 cm slender schooling fish does not have the same space, behaviour or waste requirements as a deep-bodied 10 cm fish.

Stocking should instead consider:

• Adult fish size.
• Body shape.
• Activity level.
• Territory.
• Group size.
• Waste production.
• Filtration.
• Available swimming space.

What Size Aquarium Should You Buy?

For most beginners, the best aquarium is not simply the largest tank they can find or the smallest tank that fits on a bench.

Choose a tank that:

• Fits safely in the available space.
• Suits the adult size of your chosen fish.
• Provides enough swimming and territory space.
• Can support suitable filtration.
• Fits your maintenance budget and routine.
• Can be safely supported when completely filled.

If space and budget allow, many beginners will find a medium-sized aquarium easier to work with than a very small tank.

Browse our aquarium range, including nano aquariums, 2ft aquariums, 3ft aquariums, 4ft aquariums, 5ft aquariums and 6ft aquariums.

Continue the Beginner Aquarium Series

Once you have chosen your tank size, the next step is understanding how to keep it healthy over time.

Read:

• Setting Up Your First Aquarium: A Beginner's Guide
• How to Cycle a Fish Tank Before Adding Fish
• What Equipment Do You Need for a Freshwater Aquarium?

At Aquaholics Online, we stock aquariums and freshwater aquarium equipment with Australia-wide delivery, plus our aquarium store at Baringa on the Sunshine Coast.

Frequently Asked Questions

What is the best fish tank size for a beginner?

There is no single best size for every beginner. A tank around 50–60 litres or larger can be a practical starting point for many freshwater setups, but the correct size ultimately depends on the adult size, behaviour and requirements of the fish you want to keep.

Are small fish tanks easier to maintain?

Not necessarily. Smaller tanks contain less water, so temperature and water-quality changes can happen more quickly. Careful stocking and regular maintenance are especially important in small aquariums.

Is a 2ft aquarium good for beginners?

A 2ft aquarium can be suitable for a beginner when its actual volume and dimensions meet the needs of the fish being kept. Check the litre capacity, filtration and adult fish size rather than relying on tank length alone.

Should I buy the biggest aquarium I can afford?

Not automatically. A larger aquarium can provide more stability and stocking flexibility, but it must fit safely in your home and suit your budget, stand, filtration and maintenance routine.

Can I keep lots of small fish in a small aquarium?

Not simply because the fish are small. Adult size, group requirements, behaviour, swimming space, filtration and waste production all need to be considered when stocking an aquarium.