How to Setup an Aquarium

Setting up an aquarium can be a fun and rewarding experience, but it does require some preparation and planning to ensure the health and well-being of your aquatic pets. Here are some steps you can follow to get started:

Step 1: Having a Goal

Having a goal is the first step in a successful aquarium. 

  • What kind of fish do you want to keep?

  • What size aquarium do you want?

  • Where do you want to put it?

Being able to answer any of the above questions gives you a starting point for setting up a successful aquarium. 

The size of the aquarium will depend on the type and number of fish you want to keep, as well as the space you have available. A general rule of thumb is to provide at least 1 litre of water per centimetre of full-grown fish.

Choose a flat surface that can support the weight of a full aquarium, and make sure it is near a power source and has access to a water source. Avoid placing the aquarium in direct sunlight or near a drafty window.

The most common type of aquarium is a community tank.

The aim of a community tank is to successfully house more than one species of fish. The species of fish may or may not be found together in nature. However, all species contained within a community tank will have compatible temperature and water requirements.
This guide is written assuming you are setting up a community aquarium, but the steps can be tailored so that they still apply to any aquarium.

Step 2: The Equipment

Once you have a basic idea of what you want to achieve, then you can start looking at the equipment you’ll need to get started.

To set up a community aquarium, you’ll need:

The Aquarium

Choosing the correct aquarium for the planned community is a very important step. The aquarium itself is the foundation of the entire ecosystem. Many inexperienced aquarists often choose an aquarium that is too small for the number and/or types of fish that they wish to keep.

Without the correct foundations, the system is destined for failure.

To choose the correct size aquarium there are some rules of thumb that can be used as a general guide. These are:

  • Fish in an aquarium should be able to fit in an aquarium with a minimum of 5 times their body length in swimming space. This is for ethical reasons.

  • For biological loading, there is a maximum of 1 litre for every 1 centimetre of fish in the aquarium. The number of fish in an aquarium is determined by the size of the aquarium and the biological capability of the filter.

The Filter

If the aquarium is the foundation, then the filter is the frame that supports all of the biological load on the system. It does this by supporting the nitrifying cycle, as well as collecting debris.

If a filter is undersized for the system, it will result in high ammonia and/or nitrite, which causes fish death.

An appropriate filter typically has a flow rate of about 3 times the capacity of the aquarium per hour.

Canister and sump filters, with greater biological capability, can filter a system with a slower flow rate compared to an internal filter due to their increased surface area.

Slow flow rates can be supplemented using wavemaker pumps. However, a wavemaker does not increase the filter’s capability.

See our range of filters here.

The Heater

Almost all fish are exothermic (cold-blooded), meaning they need to source heat from the environment to stay warm.

The temperature requirements of the aquarium can vary depending on which species of fish are kept.

Some fish, like Goldfish, White Cloud Minnows, and even Black Widow Tetras, can live in cooler temperatures which can often be sustained by the ambient room temperature.

However, tropical community fish require higher temperatures which can be maintained through an aquarium heater.

Most aquarium heaters come in the form of a submersible rod. The size of the heater is determined by the size of the aquarium, with 1 watt of power typically being able to easily heat 1 litre of water.

Using this rule of thumb, a 300w heater is required to heat a 300-litre aquarium.

It is always recommended to get a heater that may be slightly ‘too big’ than slightly ‘too small’ as modern aquarium heaters are thermostatically controlled. This means that once the heater reaches the set temperature, it will turn itself off until the temperature lowers again.

Having a ‘too big’ heater will run for less time, consuming less power. It will also be more effective in colder room environments.

Having a thermometer in the tank is a quick and easy way of making sure the heater is working and heating to the correct temperature.

This is my first aquarium. Are tropical fish more difficult?

This is a common question we receive in our store. The simple answer is: No, not really.

The only significant difference in caring for tropical fish instead of coldwater fish is the addition of a heater to your equipment list.

Other than that, all of the chemistry and the caring of the fish remain the same.

In fact, I would personally recommend a beginner start with a tropical aquarium as there is much more variety in fish. The fish are also often physically smaller, so they can fit in smaller desktop aquariums and they produce less waste (which makes maintenance easier).

What Temperature Should I Set my Heater to?

Finding the correct temperature in a community tank is a delicate balancing act. Most tropical community fish are comfortable anywhere between 24 - 28°C.
Setting the temperature to 26°C is a good starting point for most aquariums.

Running the aquarium warmer typically results in the fish having a higher metabolic rate and greater immunity to disease. However, more experienced aquarists will run the aquarium at a cooler 24°C due to the reduced rate of algae growth.
Having an aquarium at a cooler temperature will require greater care to help avoid causing stress and disease to the fish.

See our range of aquarium heaters here.

The Lighting

Lighting is not necessarily required for an aquarium. Fish are not reliant on light to survive. However, there are a lot of benefits to having lights on an aquarium.

The fish will get a proper day and night. Having a proper day and night lighting is good for the behaviour of the fish as they, like us, have sleep cycles.
Setting up day and night lighting can be done simply through the use of a mechanical timer, or through the use of smart light.

The length of ‘daytime’ in an aquarium can be anywhere between 8 - 12 hours.
The hours that the lights are on in an aquarium don't necessarily have to coincide with the actual day hours. Many people adjust their day hours so that the lights are on at the hours they are most likely to be home.

Be sure not to leave the lights on for too long as excess lighting can cause unwanted Algae Growth.

Having lighting allows you to grow plants in the aquarium. Plants are dependent on light for photosynthesis.

For more info about growing plants, see our article here:

Lighting does dramatically increase the aesthetics of the aquarium. Not only does it allow you to see the fish more clearly, but it helps bring out the fish's colour. Bright lights over an aquarium can darken the pigments of many fish species, making their colours brighter.

Step 3: Make it look nice

Once you have all of your equipment for the type of aquarium you are setting up, the next task is making the aquarium look nice.

Add décor and plants.

You can add decorations such as rocks, caves, and plants to create a natural environment for your fish. Artificial plants are also an option if you don't want to deal with live plants.

Substrate refers to anything that covers the bottom of the aquarium. Substrates look good, help create a more natural environment, and house beneficial bacteria.

Gravel, Sand, or AquaSoil are used as substrates. Which one you use is often a personal preference. AquaSoil is recommended if you aim to grow live plants.

Experiment with various rocks, wood pieces and ornaments to create the ideal habitat for your fish.

Step 4: Cycling the Aquarium

Cycling an aquarium is the process of developing the nitrogen cycle in a new aquarium to prevent new tank syndrome (Sounds Complicated, but it's really not).

It is important to allow the nitrogen cycle to establish in the tank before adding any fish.

The Nitrifying Cycle

The Nitrifying Cycle is the backbone of any aquarium ecosystem. Ammonia, produced by fish urea and proteins are converted into Nitrites through Nitrosomonas bacteria.

Ammonia in both its forms is toxic (NH3 and NH₄⁺).

Nitrites (NO2) are the most common killers of aquarium fish. Nitrites are the result of the partial oxidation of ammonium ions. 

Nitrites are then converted into Nitrates (NO3-) through Nitrobacteria.

Nitrates (NO3-) are the end product of the oxidation of nitrogen compounds.
Most aquarium inhabitants are tolerant of large quantities of nitrates, however, high levels should still be avoided.

Nitrates in an aquarium are removed through normal routine 10% weekly or 20% fortnightly water changes.

You can use a water testing kit to monitor the levels of ammonia, nitrite, and nitrate in the water.

Aquatic plants, due to their active use of nitrogen, help remove nitrates. In an unplanted tank system, the aquarium owner is the sole remover of nitrates through regular maintenance.

How to Cycle an Aquarium

There are two methods for cycling an aquarium. With, and without fish.

Fish-in Method

The Fish-in cycling method uses fish waste as an ammonia source. Once the aquarium is set up, let the aquarium turn over the water for about 1 to 2 weeks to allow a baseline of bacteria to form.

After that, the first few fish are added. As the fish are fed, they will produce small amounts of ammonia. The ammonia will then feed the beneficial bacteria. After a few days or weeks, the beneficial bacteria will start populating the aquarium in higher numbers.

Cycling without fish

The cycling process without fish is the preferred method as it lessens the risk to the animals. The process without fish is very similar but requires another source of ammonia. The ammonia source is often provided by Aquasoil or by the addition of ammonia chloride. Fish food can also be used as an ammonia source, although is very messy as it can also produce high phosphate levels, which often results in algae.

Using bacteria starter products such as API Quick Start, or Seachem Stability can help populate a new aquarium with the appropriate bacteria.

The entire cycling process can typically take 4-6 weeks. This is normally how long it takes for the bacteria levels in the aquarium to reach full strength. What this means is that you shouldn’t throw in all of your fish at once, but instead build your population slowly to avoid new tank syndrome.

New Tank Syndrome

New tank syndrome is the result of an aquarium without a fully developed nitrogen cycle, or the cycle has fallen out of balance.

Maintaining the nitrogen cycle is about balancing the fish, fish food, and other sources of ammonia, with the Nitrosomonas bacteria that are responsible for breaking it down.

The syndrome can be sometimes identified by white clouding in the water but is more accurately indicated by rising nitrite or ammonia levels in the water.

Nitrite and Ammonia are toxic for fish and can be fatal. The water parameters in a new aquarium should therefore be checked regularly.

Ammonia or Nitrite Reading


0.0 mg/l


>0-0.5 mg/l

Action required

0.5 mg/l


1.0 mg/l


2.0 mg/l


5.0 mg/l


New tank syndrome is mostly associated with new aquariums. However, new tank syndrome can also be present in previously well-biologically established aquariums. This typically happens following disease treatment, filter change, or incorrect cleaning of the filter material.

If an ammonia or nitrite issue is present, action must be taken immediately or risk permanent respiratory or neurological damage to the animals present.

The biological filter will remove ammonia and nitrite, but additional bacteria may have to be introduced to help it work more effectively.  This can be done using Seachem Stability or API Quick Start.

Free ammonia (NH3) is toxic to nitrifying bacteria, so a high pH level may have to be rectified to allow the biological filter to establish.

Ion exchangers remove ionized ammonia and nitrite, but only in freshwater. Materials such as Zeolite, found in Aqua One ChemiZee can be used to help quickly remove ammonia. Products like API Nitrazorb work similarly but are made from synthetic material.

Ammonia-removing conditioners, such as double dosing Seachem Prime, can be used to temporarily detoxify ammonia to provide some relief to the animals while the issue is being rectified.

Step 5: Introduce your fish and enjoy.

You can relax because the hard bit is over.

Once the aquarium has cycled, it means it is now ready for fish (yay).

Choosing the correct fish is important to a successful community aquarium. Make sure the fish are compatible to avoid conflict within the aquarium.

There are a few rules of thumb for making sure fish are compatible:

  • Fish are opportunistic feeders, so any fish that can potentially fit inside another’s mouth will most likely be eaten.

  • If introducing territorial fish such as Bettas, Angelfish, Apistogramma, etc, make sure you have enough room for them to form their territories without other fish getting in the way.

If you’re not sure about compatibility, always ask!

An experienced aquarist may choose fish based on similar colour, body shape, or geographical origin.

Another technique used for making an aquarium appear more alive is to take advantage of the layers. Some fish will stay on top of an aquarium, whilst others will stay at the bottom, and some in the middle.

Introduce them gradually, a few at a time, and make sure the water temperature and conditions are suitable for them.

Remember, each type of fish has its own specific requirements, so it's important to research the species you want to keep and provide them with the appropriate environment.