Getting a new fish is always exciting. You may want to put your new fish in the tank immediately. Unfortunately this isn’t a great idea. Adding a new fish to your tank is a slow process and there are a number of things that need to be taken into consideration first. Cycling your tank can take 4-6 weeks and is very important to ensure the survival of your pet! We will discuss cycling your aquarium in this article.
Foremost, the newly installed tank should be up and running for a few days to make sure that all the equipment is working correctly, and the tank is free from leaks. After checking your system, these are the three key steps to take when adding new fish to the tank:
1. Cycle the aquarium
2. Test the water and ensure the aquarium has cycled
3. Acclimatize the new fish.
Each one of these steps are just as important as the last so make sure you follow them when adding new fish to your tank.
Unlike humans, fish breath in the same water they go the toilet in. Fish excrement breaks down and produces ammonia. Ammonia, if left in the water can become toxic to fish and will even kill them if it reaches high levels of concentration.
To prevent ammonia build up the aquarium needs a nitrogen cycle. The cycle takes care of harmful bacteria such as ammonia, nitrite and nitrate. Cycling is the process of the good bacteria colonies within the tank processing the toxic waste and turning it into non-toxic waste. Kick starting the nitrogen cycle can take a long time. In total this could take up to six weeks to fully complete.
The easiest way to understand cycling is that you feed your fish, the fish ingests its food and then produces waste matter. All of the decomposed waste turns into ammonia which can be toxic to the fish. Then the good bacteria, in your gravel bed and filter, will consume the ammonia and nitrates and convert it into nitrates. Nitrates aren’t bad for your fish at low levels but can cause issues at higher levels. Regular water changes will keep your nitrate levels low.
To start cycling you need to have your aquarium set up, this includes making sure there is gravel in the tank, aquarium is filled with water and that the filter is switched on. The good bacteria will already be present within the water! There are a number of kits that can help kickstart your cycling process and we highly recommend using them. It ultimately simplifies the process and is more humane than cycling your aquarium with fish. You can add plants to your aquarium at this stage, they are relatively unaffected by short term water parameters and can aid in the cycling process.
While your colony of good bacteria grows you need to be patient and wait before adding new fish into the tank. In the mean time continue to test the water and monitor the ammonia and nitrate levels. You will notice a large spike in nitrite followed by a gradual increase in nitrates. This is usually a good indicator the cycle has almost complete.
While you wait, do your research into the fish you want to purchase for your tank. Be sure to select fish that are an appropriate size (fully grown) and will be compatible with each other (and water quality). Do not add your new fish into the tank until the tank is ready.
For further information on how to cycle your tank, follow our guide here!
Hopefully your cycle has now completed! A rise and fall in nitrites, followed by a rise in nitrates is usually a good indicator the cycle has completed (however this can sometimes deviate).
A testing kit can be purchased at all good pet shops, these include testing strips and an information key to help show you understand the results. Your cycling process will be complete when the ammonia and nitrite levels are at zero. The ammonia and nitrite concentration levels should stay at 0 and the nitrate should stay below 40 ppm. Nitrate levels Se the key inside the testing kit to help you understand the results better. Keep testing the water for a few days and if they continue to stay roughly the same results then you know that the cycle has worked, and you can start adding new fish to your tank.
Once your fish are settles in your tank the good bacteria
will continue to grow and deal with, he toxins, you can help by removing and
changing 25% of the water each week. This will help to keep the tank and the
water clean and stop your fish ingesting harmful toxins.
For more information on water quality and parameters follow our guide here!
Unfortunately, it is very common for fish to die shortly after
being added into a new tank. This could be because the fish itself was unwell
when purchased, but it could also be because the new owner did not correctly acclimatize
their new fish to the tank. Adding new fish to your tank can be tricky, a lot
of people place the fish in it’s bag in the new tank, leave it for a few hours
and then add it to the water, this isn’t a good way to acclimatize your fish.
When you bring your new fish home, turn down the lights in
the tank to avoid damage or shock to the fish’s eyes. When adding new fish to
the tank you should keep the fish in the plastic bag but roll the edges down
and place it in the tank water to float. This way it was float steady on top of
the water and some of the water that is already in the tank will splash over
into the bag. The next thing to consider is the pH levels, even a small
difference such as 0.5 in the pH level then this could be fatal to the fish. If
the pH levels are close within two tenths then they will equalize very fast, if
they aren’t as close it will take longer. When adding new fish to the tank
wait, the waters pH levels being equal with give your fish the best chance at
Acclimatizing is a slow process, you should gradually add
cups of water from the tank to the bag through the first two hours of the bag
floating in the tank. This will help the pH levels to slowly change so it isn’t
such a shock to the fish’s body at once. While you are waiting on the pH levels
to equalize you can focus on the water temperature. Tropical fish flourish best
in waters that are between 76° and 80°F, it’s very important to keep these
temperatures so make sure your tank has a precise thermometer. Remember that
all species of fish are have slightly different needs so check with the
specific species as to what temperature they require before you place them into
It’s very important to get your water and tank ready before adding
new fish. This could be the difference between a healthy, content fish and a
sickly fish or even worse, death. The last thing you want is your new pet to
suddenly take sick, especially when it’s something that you could prevent
yourself. Remember to take the correct steps to cycle and test your water, and
to take the time to correctly acclimatize your fish. If you follow these steps,
adding new fish to your tank will be the easiest thing in the world.