How To Know When Your Aquarium Is Ready For Fish?

Providing the perfect aquarium conditions is crucial to ensure that your aquatic fellows will be happy, healthy, and will enjoy a long life.

Conducting thorough research about your tank and what it needs is your number one task even before you buy the fish.

In fact, you need to know what exactly your selected fish will need before you set up the tank and introduce it to your fish.

You will know your aquarium is ready for fish when it tests 0ppm for nitrites towards the end of cycling your tank. It takes 4 – 6 weeks to cycle your tank.

This means the water is able to reach the best chemical balance, so your fish can survive and thrive in it. The length, of course, depends on the tank size, the water temperature, and water levels.

Below, we are going to look in detail at when to know that your aquarium is ready for fish…

How To Know When Your Aquarium Is Ready For Fish?

This is probably question number one on every new hobbyist’s mind – how to know when their aquarium is all set up to be inhabited.

A tank is ready for use after it’s fully cycled, which usually takes between 4 and 6 weeks.

At this time, the water obtains the needed colony of beneficial bacteria living in the tank’s filter and the substrate that neutralizes toxic ammonia in the water.

Thus, the aquatic environment is healthy and ready to welcome its new inhabitants.

When you place your fish in the water it will start producing natural waste, aka ammonia. If the ammonia stays in the water for too long, it begins to pile up and turns toxic.

Eventually, the water will become poisonous which will be fatal for the fish.

The beneficial bacteria established via successful cycling eliminate the ammonia by converting it into a much less toxic nitrate.

Where To Begin Setting Up Your Aquarium?

There are many things you have to do to prepare your tank before introducing fish to it:

  • Decide what fish you are going to buy.

Yes, that’s right. Before you begin any preparation and even before you buy the aquarium, you need to know the exact type(s) of fish that are going to inhabit the tank.

Is it small or big fish? Active swimmers or more lethargic ones? Will they need more space or not really? What’s the tank size your space at home allows? How many fish will you introduce to each other? What kind of decoration will you need and how much of it?

These are most of the questions you will need to answer yourself before you proceed to the actual shopping. Once, you have those cleared out, you can proceed to step number two.

  • Pumps, plants, decorations, and aeration.

Depending on the size of your aquarium, find out what types of filters and pumps you need to clean the water with and ensure sufficient water movement. It’s important to provide sufficient aeration to make sure there is enough oxygen entering the water.

  • Buy suitable plants, decorations, and pebbles. Plants are also very important for the cycling process as they play their role in the formation of beneficial bacteria.
  • Provide enough decorations to create as much natural environment as possible. Place pebbles and stones on the tank’s bottom. Fish also enjoy caves as they use them for hiding places.
  • Set up the water heater, start the filer, and add the rest of the substrate, if any. The substrate is another word for decorations and objects used mainly for aesthetic purposes.
  • Cycle. You are now ready to begin the cycling process! Once your filter is on, the water movement will begin thus starting the process. Eventually, the formation of beneficial and healthy bacteria will begin piling up on the plants and ornaments.

It may be a good idea to add a bit of food to the water. This is done to encourage the beneficial bacteria to feed on ammonia as your new tank doesn’t have an ammonia source yet.

How Can You Speed Up The Cycling Process?

Four-six weeks is a long time and waiting for the cycling to complete might end up being frustrating for you. You can apply a couple of tricks to speed up the process a bit.

Use a cycled filter – this means that you can use a filter that has been working in another tank beforehand. In this way, there will already be beneficial bacteria in the filter and ammonia can be broken down from the start. A good idea might be to ask your store if they sell any pre-cycled equipment you could use.

You can add bottled bacteria to the water. You can just buy bacteria and add it straightway to the water instead of waiting for it to form naturally.

Testing The Tank

Finally, after 4-6 weeks, you need to test that tank to find out if the cycling process has been completed. The number of weeks is different for all tanks as it might depend on the size, water temperature, and oxygen levels.

Before adding the fish, you need to check 3 thingsammonia, nitrite, and nitrate. These are the three components of the nitrogen cycle in the water. You can test them yourself with a test kit or you can ask your local store to do that for you if you are feeling insecure about it.

Ammonia – there should be very little to no ammonia at all in the tank. Anything close to 1 part per million is fine but anything above 1 or 2 ppm is already too much.

Nitrite – nitrite should also be close to 0. If the cycling has been successful, the nitrite level should be zero.

Nitrate – nitrate is less toxic and harmful in comparison to the previous two, so you don’t need to worry this much about it. With a good cycle, you will have some nitrate. However, if it is above 40ppm, you should perform a water change.


After completing the abovementioned steps, you are all ready to introduce your first fish to the tank! Since the beneficial bacteria are still in their early stages do not stock up the whole aquarium with fish straightway but build up the population gradually.

To sum up, your aquarium is ready for fish when the cycling process has been completed. This takes up between 4 and 6 weeks.

The period length depends on the tank size, water temperature, and oxygen levels. Provide the necessary plants, decorations, pump, and filter.

Once everything is set, put the filter to work and let the cycling process begin.

After 4-6 weeks test the water and check the ammonia, nitrite, and nitrate levels. If they are as they should be, then slowly start introducing fish

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