Bringing a new, scaly family member home will be one of the most enjoyable experiences you will have. Preparation and knowledge is key to making fish ownership as easy as possible as well as keeping your fish happy and healthy for life!

Is a Fish the Right Pet for You?

First things first. Are fish the right choice for you and your lifestyle? Fish require less daily attention and feeding requirements than dogs and cats, so if you are someone that is out of the house for most of the day a fish may be a great pet choice for you. However in general, fish tanks do need regular attention in relation to their cleaning and maintenance. As long as you are prepared to maintain your tank and in turn, your fish community’s health, then jump right in!

How to Choose a Fish Tank

When choosing a tank, consider five important factors

  1. Space in your home

    Ensure the tank you choose has enough space in your home, and determine where your tank will live before you make your p urchase. Purchasing a large tank for a small home may create problems if you don't know where to put it.

    Most large size tanks come with the option of purchasing a stand which is strong and suitable to hold your tank when it is full of water. Ensure you have the room for this as well, as placing your tank on a different piece of furniture may result in damage. You'll also need to ensure that the flooring beneath your tank is suitable to hold its weight when full.

    Keep your tank away from areas where external sources like windows and heater vents will affect its temperature. Also, try and keep your tank out of direct sunlight as this will promote algae growth.

  2. The amount of fish you'd like to keep

    The more fish you keep, the bigger your tank will need to be. Overcrowding a small tank with any type of fish will result in your fish either outgrowing the tank or unnecessary stress placed on the fish that can easily result in illness and/or death.

  3. The type of fish you'd like to keep

    Most fish purchased are young and not yet fully grown. Ensure your tank has ample room for your fish to grow. Different species grow to different sizes - your local PETstock fish guru will be able to chat with you about this and help determine which breed of fish is most suited to you.

  4. The time you have to maintain your tank

    The larger your tank, the longer it will take to properly care for so keep this in mind when considering how much time you'll have to maintain your fish family's home.

    For example, an aquarium of about 200L+ that is fully stocked with fish might take a couple of hours to maintain every fortnight (approximately). Maintenance frequency depends on a number of factors so this estimate may be more or less.

    Below is a rough guide of tank sizes, fish capacity and maintenance frequency.

    Tank Size Fish Capacity Maintenance Frequency
    20 Litres 2 fish Every Fortnight
    90 Litres 10 fish Every Fortnight – 3 weeks
    165 Litres 15-20 fish Every Fortnight – 4 weeks
    *Fish numbers are based on a 5cm fish size.
    Shop Fish Tanks
  5. Your Budget

    An obvious one but don't skim over it! The bigger your budget the more equipped your tank can be. There are some varieties of tanks that may be the same size but different in cost. This is mostly due to what the tank includes. The more expensive option will most likely include a built in light and filter whereas the less expensive option may have neither (a filter is essential so will need to be added if your tank does not have this). In general, most new tanks come with a light and filter built in. Your local PETstock team can help find a solution within your budget.

What do I need when purchasing an aquarium?

To make the set up process as easy as possible, you'll need the following items when purchasing your aquarium:

  • Water conditioner
  • Ammonia, Chlorine and Chloramine eliminator
  • Live Bacteria - API Perfect Start is a great kit to purchase for smaller tank sizes as an all in one set up product. It contains three envelopes of treatment to use on day one, day 14 and day 28 to ensure your tank set up is as easy as possible. Seachem Head Start is the alternative to this for larger tank sizes.
  • Conditioning salts
  • Gravel
  • Filter (if your tank does not come with one)
  • Heater (if you would like to keep tropical fish)
  • Live plants
  • Ornaments and aquarium background (optional)

Purchasing fish on the same day as your tank is NOT advisable. Letting your tank cycle for at least one week before adding fish is essential to allow the tank's natural biological filter develop. Please see How to set up a Fish Tank: A Step by Step Guide for more info.

How to set up a fish tank

  1. Remove aquarium from the box
  2. Carefully remove your tank from its box and place in a safe spot. Build your stand (if needed) at this point. While you’re able to get to the back of aquarium easily, add your aquarium background if you have purchased one. If your tank comes with a light, ensure that it is working by plugging in and turning on. You may also want to wipe down the inside of the tank with a damp cloth (free of any chemicals or soaps) to ensure there is no dust.

  3. Put your aquarium in its place
  4. Once you have built your stand and added your background, place your tank in its designated area. Doing this now will be much easier and safer than when it is full of water and very heavy.

  5. Rinse all gravel and ornaments
  6. With some hot water (free of any chemicals or soaps), thoroughly rinse your gravel and any ornaments you have purchased. This will ensure they are free of dust and any paint. Place them in the tank by adding the gravel slowly and carefully, to ensure it doesn’t hit the bottom of the tank too hard and cause damage.


    Rinse your gravel with a strainer to make the process much easier!

  7. Fill your tank
  8. Fill your tank with tap water. You may want to use a hose if possible. Begin filling the tank slowly to avoid any cloudiness from your gravel.


    Place a small plate in the bottom of your tank and slowly pour the water into the tank over the plate, to minimise cloudiness.

  9. Turn on filter (and heater if applicable)
  10. Now is the time to turn on all electrical equipment associated with your tank (do NOT do this beforehand as this will damage your electrical equipment). The light can stay off for now if you would prefer. As a general rule, only leave your light on for up to eight hours per day, as any longer may promote algae growth.

  11. Add in treatments
  12. Read all instructions on your treatment bottles to ensure you are adding the right dosage to your tank. Add in all treatments now.

  13. Let the tank cycle
  14. Allow your tank to cycle and create a healthy biological filter before adding in any fish. This may take up to one month. To begin the cycle, add a good pinch of fish food to the water; this will break down into ammonia and products promoting bacteria will start to act.

    By letting a healthy environment develop, you will decrease the chance of your tank suffering from New Tank Syndrome which is a toxic buildup of ammonia and nitrites.

    After this time, take a sample of your tank water (about 100ml, in a clean container with lid) into your local PETstock store for free water testing. A PETstock Person will ensure your water’s pH, GH, ammonia and other levels are all optimal before you add your fish. If these results are positive, it’s time to purchase some fishy family members!


Don’t be worried if your tank seems murky or cloudy for the first few weeks, this is normal and will fade in time. If this persists, ask your local PETstock team about water clarifying products. Keep reading for common causes of cloudy and green water.

Fish Tank Maintenance

To keep your fish happy and healthy, you will need to perform a few regular maintenance jobs. This includes a partial water change and water testing.

Changing your Tank Water

Because your tank is an enclosed ecosystem, waste can build up and turn toxic. A smaller tank will have this occur at a faster rate than a larger tank, as will tanks with a large fish population.
To ensure your fish stay healthy, it is recommended to do a water change every two weeks (as a guide, this may be needed more or less depending on your tank).

  • Use a gravel vacuum and bucket. A gravel vacuum acts as a siphon and removes water from your aquarium whilst getting in and under the gravel and removing excess dirt and waste.
  • Whilst the water is siphoning through the gravel vacuum, move the end that is inside of the tank all through your gravel. Keep doing this until you have removed about 25% of the tank’s water capacity.
  • If you have a tropical tank, be careful not to drop the water level as low as the heater, as having your heater switched on and out of water will cause damage and compromise its efficiency.


    Only ever change about 25-30% of the water in your tank. Removing any more will affect the biological filter. In other words: it would be like starting the set-up of your tank all over again. However, you may need to remove more if your fish have become ill.

  • Once you have taken out your water, replace this with fresh tap water. Ensure this is completed slowly, especially in a tropical tank to ensure the temperature does not change too much.
  • Treat the new tank water. Generally, you will use the same treatments you added when first setting up your tank, especially ammonia, chlorine and chloramine eliminator. Speak to your local PETstock team about which treatments you should keep on hand at all times.

Controlling Algae in your Fish Tank

Wiping the inside of your tank with a sponge or similar (free of any chemicals or soaps) will remove any algae or dirt build up.

To keep algae levels in your tank to a minimum:

  • Ensure your tank is out of direct sunlight
  • Only have your light on for no more than eight hours per day
  • Ensure your filter is up to the job

If you keep tropical fish, the addition of any catfish may also help to keep algae levels down as they like to consume this. If algae has become a problem in your tank, there are treatments available to help fix the problem.

Maintaining your Fish Tank Filter

Your filter has a number of parts that will need to be tended to. This includes:

  • Carbon - change every six to eight weeks
  • Filter cartridge - change every six to eight weeks (these normally contain carbon)
  • Sponges - maintain every two to three months. Ensure you’re rinsing in treated water as the chemicals in tap water will kill your good bacteria on contact.
  • Ceramic noodles - change every six months, ensuring enough bio-filter to sustain the tank’s system.
  • Impeller and rubber diaphragms - change when broken


The water parameters in your tank will change over time and become unsuitable for your fish’s survival. It is recommended to test these parameters on a weekly basis.

You will need to test pH, GH, Ammonia, nitrate and nitrite. You can do this yourself at home with a test kit or your local PETstock team will check them for you for free. Simply bring a tank water sample into store in a clean container with a lid.

If you find your test results to be undesirable, speak to your local PETstock Person about the best solution for you. Usually, the most common course of action is a water change or the use of pH adjusting powders.

How to choose fish for your tank

When you are ready to select your fish, speak to a PETstock Person to help decide which breeds will be suited to you. Usually, the hardiest breeds of fish are best to purchase first, as they will thrive in a new environment and continue to develop your biological filter, ready for any other fish you choose. Only purchase minimal numbers (about two) as a start, as adding too many at once may cause unnecessary stress on the fish. When purchasing further down the track, it is still recommended to purchase minimal numbers at a time.

Cold Water Fish

This type of freshwater fish is a common choice for beginners as they are relatively easier to care for than tropical fish. These fish come in many different shapes and sizes and are reasonably inexpensive. You will find them in red, white, black, multicoloured and even uncoloured varieties. Be careful when purchasing for a small tank, as some types of cold water fish grow to 20cm plus! Speak to your local PETstock team to decide which breeds are best for your tank size.

Cold water fish are associated as being a hardier type of fish, however they still need the same level of care as any other. A filter for your tank is still essential, as this is what maintains the cleanliness of their habitat. Without a filter, your tank would become dirty much more quickly, and result in unnecessary stress on your fishy family members.

Tropical Fish

Tropical fish are very popular as their range of colours, sizes and shapes is much wider than cold water fish. Their eclectic style adds an exotic feel to your tank. With a colour range from orange, red, blue, yellow, pink, black, white, spotted, multicoloured etc. (even transparent!), these are definitely a popular choice of fish to keep at home.

Tropical fish require additional hardware than that of their cold water cousins. As well as a filter, tropical fish also need:

These items help maintain their natural habitat of around 26 degrees celsius whilst keeping the water fully oxygenated (the higher the temperature in tropical tanks, the decreased volume of oxygen).

Tropical fish generally live together quite peacefully, however there are some territorial breeds and others which are quite aggressive and best kept on their own. Speak to your local PETstock team when purchasing fish to ensure they are compatible with their tank mates.

How to introduce fish to your tank

Purchasing Fish

If choosing to purchase your fish from PETstock, they will be collected in a plastic fish bag and tied in a way that traps in oxygen, making the travelling experience as easy as possible on you and your fish. After purchase, your fish will survive approximately one hour in a fish bag, so ensure you purchase your fish close to where you live and at a time when you can go straight home. The less time in the bag, the better.

How Do I Add Fish to my Tank?

When you arrive home, open the lid of your tank and float your fish, in their fish bag, on top for around 10-15 minutes. After this time, you may add your fish. When doing this, it is best to ensure that no water from the bag goes into the tank.

The reason for this is that it is possible for fish to generate ammonia while travelling, a substance you’ve already worked so hard to eliminate! It is easiest to purchase an appropriate sized fish net and simply scoop your fish out of the bag and gently place him in your tank.

Do not feed your fish for the first 24 hours after adding him to your tank and keep the light off during this time. Taking these steps will help to minimise the stress placed on your fish.

What to do if you have Sick Fish

Just like us, fish are living things and sometimes don’t feel the best. Occasionally, they may get sick and need some special attention. The most common cause of illness in fish is stress. Stress is caused by just about anything your fish finds uncomfortable; like travelling, poor water quality and over feeding. Common illnesses fish suffer from include:

  • White Spot
  • Fungus
  • Fin Rot
  • Parasitic infections
  • Ick
  • Mites
  • Lice
  • Dropsy

If you think your fish is ill, speak to your local PETstock team immediately, to help decide the best course of action. The faster you get onto the problem the best chance your fish has of surviving. PETstock has a large number of products available to rectify these situations. Ensure you read the instructions carefully on treatment bottles as some require you to remove parts from your filter first, to ensure the product isn’t filtered out!

How much food should I feed my fish?

Both cold water and tropical fish mostly eat the same type of food, however there are different varieties optimized for both types. For example, you will find fish flakes for either cold water or tropical fish. You will also find some fish foods which float, like flakes, or sink, like sticks. This is because some fish eat at the top of your tank or in the middle, and some prefer to eat from the gravel at the bottom (called bottom feeders).

In general, fish enjoy a combination of the following foods optimized for them i.e. cold water or tropical:

  • Flakes
  • Granules
  • Sticks
  • Crisps
  • Pellets
  • Frozen food
  • Frozen bloodworms
  • Algae discs – best for catfish and other bottom feeding fish
  • Live fish – optimal for large, aggressive breeds of fish like cichlids

If you are going to be away from home for more than a day or two, PETstock also has feeding options for both cold water and tropical fish that will last until you arrive home.

Be extra careful when feeding your fish, as over feeding is one of the most common causes of death.

Tips for Feeding Fish

  • Add a minimal amount of food each time as it is easy to add a little more if needed, but very difficult to remove and potentially harmful if you add too much.
  • Generally, your fish only needs to eat for 30 seconds to be satisfied, so try and stick to this guide to minimize wastage.
  • Do try and feed your fish a couple of times each day in smaller amounts, rather than once in one large amount, to keep them full and happy.
  • When you are feeding fish in a new aquarium, this feeding frequency can be decreased to keep harmful toxin levels down.


As a feeding guide, it’s good to remember that the size of the fish’s eye is roughly the size of its stomach.


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