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How do I calculate the water volume/capacity of my fish tank?


Simple multiply, in centimetres (cm), the Length (L) x Height (H) x Width (W) then divide by 1000. For example: 60 cm (L) x 30 cm (H) x 20 cm (W) / 1000 = 36 Litres.

How many fish can I put in my fish tank?

It depends on the size of the fish tank, the type of fish, how many fish, their current size, and how large they are expected to grow.

Essentially, the factors you are considering here are:

  1. Fish need room to swim (a large fish occupies more space than a small fish)

  2. Fish need clean water (a large fish pollutes water faster than a small fish)

  3. Fish need oxygen (a large fish consumes more oxygen than a small fish)


Most fish we sell will be juveniles and are expected to grow. You should do a web search on a prospective fish's "max size" to get a better approximation of the tank necessary to house it.


The most common error is assuming that goldfish can be kept in small tanks and bowls; all goldfish, whether they be comets, orandas, ranchus, moors, nymphs, ryukins, shubunkins, fantails, koi, etc., will grow quite large - even as much as 30cm or more - and can live for decades if kept properly. To keep goldfish longterm, you will need a tank of 100 litres or more.

Fish do not grow to the size of their tank; either the tank is large enough, or the fish outgrow it.

Which fish can go together?

The majority of fish we sell are community fish and can live together. However, there are some caveats, and generally speaking, curating the "Noah's Ark" tank (i.e., two of every kind) not only looks bad, but generally does not work well.


For an expert-looking, harmonious aquarium, focus on a single species with perhaps a few peripheral additions. For example, a school of 50 neon tetras and half a dozen corydoras on the bottom will look a lot nicer and be healthier than a tank with 6 neons, 4 rasboras, 3 cories, 2 barbs, 4 clouds, etc.

It can be difficult to successfully mix and match without a fair amount of personal experience and species knowledge, but a quick web search of compatible "tank mates" will help point you in the right direction.

Some of the issues you may encounter are:

  1. Size difference, e.g., 15cm oscar vs 3cm neon tetra = snack time for oscar;

  2. Aggression, e.g., African cichlid vs guppy = dissected guppy;

  3. Schooling/shoaling, e.g., inadequately sized groups can lead to reclusion and stress;

  4. Reproductive harassment, e.g., male livebearers will relentlessly harass females for breeding rights;

  5. Territoriality, e.g., some fish may become defensive over a particular area in the aquarium;

  6. Competition, e.g., some fish may not be quick enough to get food at feeding times.

Is this fish aggressive?

Aggression exists to some degree in all species of tropical fish but most of it does not amount to any serious concern. Some fish, such as African cichlids, will demonstrate considerable aggression from a young age and should only be kept with their own kind; other fish won't show aggression until they have reached maturity and are in breeding condition, which may exhibit itself as chasing intruders away from their territory. Tetras and other small schooling/shoaling fish can be seen establishing a pecking order amongst themselves.


When deciding on whether aggression might be an issue between prospective new fish, you should do a web search on "tank mates" for the species in question.


Sometimes aggression isn't the issue, but rather, perceived threat; for example, small schooling fish may perceive a large, peaceful fish as a threat and will hide and become stressed if their school is not large enough to create a sense of security. Additionally, some fish may nip out of curiosity, or may mistake flowing fins for food.

How often and how much should I feed my fish?

You can feed your fish twice per day - morning and afternoon - but only minimally. You can use the fish's eye as a rough guide to how much food to give your fish in a feeding. This will typically mean that each fish receives one or two pellets each, or a few little flakes. It is okay to skip a day or offer only one feeding on some days, it is unlikely that your fish will starve; overfeeding is very common and will quickly lead to poor fish health. Fish are grazers and will always be eager for more food, but it is important not to indulge them. Offering them some variety in their diet is recommended, so in addition to flakes/pellets, you can occasionally offer them bloodworms, brine shrimp, frozen foods, vegies, etc.

Can I go away over the weekend or on holidays without feeding my fish?

Yes, you can. We sell weekend and holiday food blocks that dissolve over a few days/weeks to slowly release food to your fish and give them something to nibble on while you are away. We also sell automatic feeders that can be set to sprinkle food in every 12 or 24 hours.

If you are only going away for a couple of days, you do not necessarily need to do anything as your fish will not starve if they are not fed for a few days. If you are going away for an extended period, use a holiday block or an autofeeder; do not instruct an inexperienced friend to feed your fish as they will most likely overfeed them.

You should do tank maintenance/a water change close to the day you are to leave to ensure clean water and filter operation in your absence. Use a friend to drop in and video call if you are concerned about your aquarium and want to observe it; alternatively, you can use an aquarium maintenance service to look after your fish while you are away.

How do I introduce new fish to my aquarium?

The basic procedure is to simply float the sealed fish bag in your tank for about 20 minutes to allow the temperatures to match and the fish to acclimate itself. After 20 minutes, you can net the fish out of the bag and release it into your aquarium; discard the water from the fish bag (do not pour it into your fish tank).

Do I need to condition or dechlorinate my water?

Your tap water will contain chlorine and should be treated with a dechlorinator. If you fail to do this, you risk killing your fish and the beneficial bacteria in your filter.

Do I need a filter?

Yes, you do. A filter provides water flow which helps oxygenate the water, in addition to providing a safe space for beneficial bacteria to populate and break down the waste produced by your fish. This reduces the frequency of water changes required and helps stabilise the aquarium.

Do I need an aquarium heater?

The vast majority of fish in the hobby are considered tropical fish and require a stable water temperature of around 25 degrees celsius. Even goldfish, which are often kept in unheated aquariums, have an ideal temperature range of 20-23 degrees celsius and will not be happy when the temperature in your house goes down to 5 degrees in the winter. A heater helps stabilise water temperature and only operates when water temperature falls below the temperature set for the heater; in warmer months, the heater may not operate at all.


Having a heater will make life easier, as most fish and aquatic plants require it, and higher temperatures are also helpful in treating some diseases. Bristlenose, and most other sucker mouth catfish, that do such a fantastic job of algae control, typically require a heated aquarium.

How do I cycle my new aquarium?

Cycling is a process that happens naturally over several weeks whereby the beneficial bacterial population inside your tank and filter builds up to a point where it can readily digest waste produced by your fish into a less toxic form known as nitrate. This process is called the Nitrogen Cycle, where the starting product, Ammonia (NH3), is broken down into a less toxic secondary product called Nitrite (NO2-), and then finally into an even less toxic product called Nitrate (NO3-), which must be removed from your aquarium with water changes. A fish tank won't cycle unless there is some waste being produced in the tank to feed the bacteria, so adding a couple of fish, or even just fish food, can start the cycle; there are some products on the market that will quickstart the cycle by adding a dose of beneficial bacteria straight into the tank. Water cloudiness is a common sign of a new aquarium that hasn't been cycled, which is caused by an algae bloom taking advantage of the excess fish waste.

Do I need to wait a period of days/weeks before adding fish to my new aquarium?

So long as you have added dechlorinator to the water and allowed the fish to acclimate to the temperature, then it is okay to add a few fish (e.g., one or two goldfish, or half a dozen tetras). However, you should observe the success of these fish and allow the good bacteria to grow on your filter media for at least two months before adding more fish.

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