Setting Up Your First Aquarium: A Beginner’s Guide

Setting up your first aquarium is exciting, but taking a little time to get the basics right can make fishkeeping much easier.

A successful freshwater aquarium needs more than just a tank and some fish. You will need suitable filtration, stable water conditions, the right temperature, appropriate stocking and a simple maintenance routine.

This beginner aquarium guide takes you through the process step by step, from choosing your first tank to adding fish safely.

1. Choose the Right Aquarium Size

Small aquariums can look easier to manage, but larger tanks are generally more forgiving because changes in temperature and water quality happen more slowly.

For many beginners, an aquarium around 60 litres or larger is a practical place to start if space and budget allow.

When choosing an aquarium, think about:

• The adult size of the fish you would like to keep.
• How many fish the aquarium can comfortably support.
• The space available in your home.
• The weight of the aquarium once filled with water, substrate and decorations.
• Whether you want a planted, community, cichlid or specialised aquarium.

You can browse our range of aquariums and fish tanks if you are still deciding what size will suit your setup.

2. Choose a Suitable Location

Choose the aquarium location before filling the tank. Even a medium-sized aquarium becomes extremely heavy once it contains water, substrate and decorations.

A good location should be:

• On a strong, level aquarium stand or suitable cabinet.
• Away from prolonged direct sunlight.
• Close to a safe power source.
• Easy to reach for water changes and maintenance.
• Away from areas with large temperature fluctuations where possible.

Direct sunlight can encourage excessive algae growth and may contribute to unwanted temperature changes.

3. Rinse the Aquarium, Substrate and Decorations

Before setting up the tank, rinse new substrate, rocks and suitable aquarium decorations with clean water where required.

Avoid using household detergents or cleaning chemicals inside the aquarium. Residues can be harmful to fish and other aquatic animals.

Add your substrate first, followed by rocks, driftwood and other hardscape.

If you are planning a planted aquarium, this is also a good time to think about where your plants will be positioned. Browse our live aquarium plants and aquascaping supplies for ideas.

4. Install the Filter

Filtration is one of the most important parts of a healthy aquarium.

A good aquarium filter performs several jobs:

• Moves water around the aquarium.
• Collects suspended debris.
• Provides surface area for beneficial bacteria.
• Helps maintain stable water quality.

Choose a filter that is suitable for your aquarium size and the type of fish you plan to keep.

Our aquarium filtration range includes internal filters, external filters, sponge filters and filter media for different aquarium sizes and setups.

5. Install a Heater if Your Fish Need One

Many tropical freshwater fish require stable warm water, so an aquarium heater is commonly needed.

The correct temperature depends on the species being kept. Do not assume every tropical fish requires exactly the same temperature.

Use an appropriately sized heater and monitor the aquarium temperature with a thermometer.

You can browse our aquarium heaters for tropical and freshwater setups.

6. Fill the Aquarium and Treat the Tap Water

Fill the aquarium slowly so you do not disturb the substrate or hardscape.

If you are using tap water, use a suitable aquarium water conditioner to neutralise chlorine and, where applicable, chloramine according to the product directions.

Once filled, start the filter and heater and check that everything is operating correctly.

7. Cycle the Aquarium Before Adding Fish

This is one of the most important steps in setting up a new aquarium.

Fish and other livestock produce waste that eventually creates ammonia. Ammonia is toxic to fish.

In an established aquarium, beneficial bacteria convert ammonia into nitrite and then convert nitrite into nitrate. This process is commonly known as the aquarium nitrogen cycle.

A new aquarium does not immediately contain a mature population of these beneficial bacteria.

For this reason, you should not judge whether an aquarium is cycled simply by counting the number of days it has been running.

Use an aquarium water test kit to monitor:

• Ammonia.
• Nitrite.
• Nitrate.
• pH where appropriate.

The goal is to establish a biological filter capable of processing the waste that will be produced by your livestock.

Cycling times vary depending on the method used, temperature, bacterial population, filter media, water chemistry and other factors.

8. Choose Fish That Suit Your Aquarium

Once the aquarium is ready for livestock, choose fish based on their adult size and care requirements rather than how small they are in the shop.

Consider:

• Adult size.
• Minimum aquarium size.
• Water temperature.
• pH and water hardness preferences.
• Temperament.
• Whether the species should be kept alone, in pairs or in groups.
• Compatibility with the other fish in the aquarium.
• Swimming level and available space.

There is no single list of fish that is suitable for every beginner aquarium. A fish that works well in one community may be completely unsuitable for another.

Browse our current live freshwater fish range and check the care information for individual species before deciding what to add.

9. Add Fish Gradually

A newly established biological filter has a limited capacity. Adding too many fish at once can cause ammonia or nitrite levels to rise.

Start gradually and continue testing the water as livestock is introduced.

Monitor new fish for:

• Normal swimming behaviour.
• Healthy appetite.
• Rapid breathing or gasping.
• Clamped fins.
• Spots, lesions or unusual marks.
• Aggression between tank mates.

10. Establish a Simple Maintenance Routine

Once your aquarium is established, regular maintenance helps keep water quality stable.

A typical routine may include:

• Testing water regularly, particularly in newer aquariums.
• Performing partial water changes as required.
• Removing debris from the substrate.
• Cleaning algae from the glass.
• Checking filter flow.
• Cleaning filter media correctly when required.
• Checking the heater and temperature.
• Observing fish for changes in health or behaviour.

Avoid replacing all filter media at once unless there is a specific reason to do so. Much of the aquarium's beneficial bacterial population can live within biological filter media.

Common Beginner Aquarium Mistakes

Adding Fish Too Soon

A clear aquarium is not necessarily a cycled aquarium. Water testing is much more useful than appearance when determining whether the biological filter is functioning properly.

Adding Too Many Fish at Once

Stocking gradually gives the biological filter time to adjust to increasing waste production.

Overfeeding

Excess food can break down in the aquarium and contribute to poor water quality. Feed an appropriate amount for the species being kept rather than automatically adding more food.

Our fish food range includes foods for a wide variety of freshwater aquarium species.

Choosing Fish Based Only on Appearance

A small juvenile fish may eventually become too large, territorial or unsuitable for a community aquarium. Always check adult size and compatibility before buying.

Replacing All Filter Media at Once

Replacing or over-cleaning biological filter media can remove beneficial bacteria and reduce the aquarium's ability to process waste.

Making Large Changes Too Quickly

Fish generally benefit from stable conditions. Large or sudden changes in temperature, water chemistry or aquarium environment can cause unnecessary stress.

Your First Aquarium Checklist

• Suitable aquarium and stand.
• Filter matched to the tank and livestock.
• Heater if required.
• Thermometer.
• Substrate.
• Suitable rocks, driftwood or decorations.
• Live plants if desired.
• Water conditioner.
• Water test kit.
• Appropriate fish food.
• Gravel cleaner or siphon.
• Bucket or other aquarium maintenance equipment.

Setting Up Your First Aquarium Doesn't Need to Be Complicated

The most important thing is to take your time.

Choose an aquarium that suits the fish you want to keep, install suitable equipment, establish the biological filter, test your water and add livestock gradually.

Once the aquarium has settled into a regular routine, freshwater fishkeeping can be an enjoyable and rewarding hobby.

At Aquaholics Online, we stock aquariums, filtration, heaters, live aquarium plants, fish food and freshwater aquarium fish, with Australia-wide online delivery and our aquarium store at Baringa on the Sunshine Coast.

Frequently Asked Questions

How long should I wait before adding fish to a new aquarium?

There is no fixed number of days that guarantees an aquarium is cycled. Use water testing to confirm that the biological filter is processing ammonia and nitrite appropriately before stocking the aquarium.

What size aquarium is best for a beginner?

There is no single ideal size, but an aquarium around 60 litres or larger is often easier for beginners to manage than a very small tank because water conditions tend to change more gradually.

Do all freshwater aquariums need a heater?

No. Whether you need a heater depends on the species being kept and the temperature of the room. Many tropical fish require heated water, while some temperate species do not.

Do I need a filter in my first aquarium?

Most freshwater aquariums benefit from suitable filtration. The filter provides water movement, mechanical filtration and an important home for beneficial bacteria.

How often should I change aquarium water?

The appropriate water-change schedule depends on stocking level, feeding, aquarium size, filtration and water test results. Regular partial water changes are generally preferable to waiting until water quality becomes poor.