How to Introduce New Fish to My Aquarium? The Right Way!

Moving into an entirely new home or environment can turn out to be a massive shock for just about any creature, but it is even more stressful for our little scaly fish friends.

Not only will they be in an entirely new place, but the water quality will likely be very different as well. Even very minute changes in water temperature, pH levels, and many other factors can potentially make a really huge difference in the life of a fish.

In order to keep your fish both safe and healthy, you will have to take certain measures when introducing them to a new aquarium tank.

While adding new fish to your aquarium might be an enjoyable experience, you will have to understand that without the requisite precautions, your fish might become sick, or they may even die.

This is why it is absolutely imperative that you should first prepare your aquarium properly before adding them to the water tank.

This is what you should do when introducing new fish to the aquarium:

Wash the Rocks, Gravel, and Other Ornaments

You will need to drain and thoroughly clean your tank and all of its contents (such as decorations) before you place any fish in it.

However, you should refrain from using either soap or any detergents in order to wash the rocks, gravel, or ornaments. Simple lukewarm water will suffice. This will get rid of the bacteria, dirt, and many toxins.

The best way to wash the gravel is by placing it in a large colander. Place the colander over an equally large plastic pan or a small bucket and proceed to add the warm water to the colander while mixing in the gravel.

After that, you should stir the gravel around and drain the water. You should repeat this process multiple times until the water is clear and clean. This will ensure that all the pollutants have been completely removed from the gravel.

You should just rinse the other items in the water. Once they are clean enough, you should add them back into the tank. You must always ensure that the gravel is very evenly distributed all over the bottom of your fish tank.

You might consider placing the rocks and the various other ornaments in odd corners of the tank so that they make ideal hiding places that your fish would love to explore.

Fill the Tank with Water

You can use a clean bucket or a water hose to pour water into your aquarium tank. It is a good idea to place a plate or a large flat saucer over the gravel when you start pouring in the water. This will ensure that the gravel will not move around.

Once you have filled your water tank up to about one-third of its capacity with room temperature water, you have to add a water conditioner to the mix. Any conventional dechlorination can do the job easily enough, and it will help to remove the excess chlorine from your fish tank.

Always remember that chlorine in the tank water is a deadly combination for your fish since natural fresh or saltwater does not contain this chemical. Chlorinated water can easily lead to a whole lot of health issues.

You might notice that the water will start to turn cloudy within the first 48 to 72 hours after it has been filled. This is due to the growth of the bacteria that will start thriving in the dechlorinated environment.

That said, there’s nothing to worry about since it will eventually disappear on its own.

Time to Connect the Air Pump

Don’t forget to connect the air pump in the tank to make sure that the environment in the aquarium is sufficiently oxygenated. You must not try and introduce new fish to the aquarium until you are absolutely sure that the pump is up and working.

It is a good idea to purchase and use an off-the-shelf aquarium check valve. This is a very small valve that is located outside the tank to hold the air tube.

If properly placed, this valve will allow you to place the air pump directly and seamlessly underneath the aquarium. The no-return valve will also prevent the water from backing up into the tank in case the power has been switched off.

Add Plant Life

Both live and artificial plants have an important role to play in your aquarium prior to the placement of your fish in the water tank. Live plants are a great way of circulating oxygenated water in the tank. Plastic plants are important too because they create hiding places for the fish.

Moreover, you can also use both live and plastic plants to hide your vital equipment and give the whole aquarium a uniformly aesthetic appearance.

If you have purchased your aquatic plants beforehand, it is a smart idea to keep them moist by wrapping them completely in several layers of wet newspaper.

When you decide to plant them, you should make sure that the roots of the plants are way below the surface of the gravel. It would be a good idea to make sure that they have touched the bottom of the tank.

However, the crown of the plant must be exposed to the water. You might also consider applying an aquatic plant fertilizer to the mix so that your live plants will be able to thrive and grow very well.

Also read: How To Anchor Aquarium Plants?

Transporting the Fish

You should keep your fish someplace nice and dark for the trip home. If the pet store has not covered the clear plastic bag, it is important that you do the needful and place the water container in an opaque paper or plastic bag.

The fish can become really stressed if they see their whole world moving all around them. Under the circumstances, it is important to reduce the stress of the trip as much as possible.

You should also try and shorten the trip as much as possible. Fish can lose their color from stress, and it will take them a lot of time before they recover their usual brilliant hues and shades.

Once you get home with the fish, you should place the clear bag that contains the fish in the aquarium and just simply let it float around unopened for around half an hour or so.

If you have an old tank and it already has a number of aquatic creatures, you should move the decorations around a bit. This will help break up the territories of those fish that were already in the tank beforehand. The last thing you want is multiple fights between the old and the new fish as they try to become top dogs in their tiny world.

After you have had the bag floating in the tank for some time, the water temperature would have stabilized. This will acclimatize the new fish to your aquarium tank’s temperature. Moreover, they would have been able to see the world where they would live so they won’t be stressed out too much

Never Dump Pet Store Water with the Water in Your Tank

This step cannot be emphasized enough. You must not dump the fish, water, and all into your tank. On the contrary, you should open the bag very carefully so that the fish don’t spill out and scoop the water from the water tank into the bag.

Now that the tank and the store water have mixed in the bag, let the bag float around in the tank for a bit longer.

Cycle the Water in the Tank with the Help of a Water Cycling Kit

Cycling the water in the tank will help balance out many harmful chemicals such as ammonia and excess nitrates that are produced by the fish in the tank. This process will also introduce certain types of bacteria that will break down and eat most of the present harmful chemicals in the water.

Here, it is pertinent to note that you should cycle the water in the tank for at least a month so that your aquarium would be able to maintain a very healthy chemical and biological balance.

If you were to do this before you add your fish to the aquarium, you would be able to help ensure that the fish will stay happy and very healthy in their new aquatic environment.

Cycling the tank from scratch for the very first time might lead to a buildup of ammonia around the second or third week or so.

After the ammonia levels have decreased, the nitrite levels will increase even as the former’s levels will drop to near-zero. Finally, both the nitrite and ammonia levels will disappear, and they will be replaced with nitrates.

This is considerably less toxic than ammonia or nitrites. This is because you can actually control the level of nitrates with regular maintenance of the water present in the tank.

Always remember that a clean and healthy fish tank should not show a positive reading for any of these chemicals. Introducing new fish in an aquarium full of harmful chemicals will drastically shorten the lifespan of your fish.

Turn off All the Lights Present in Your Fish Tank

Bright lights in an all-new environment will create a lot of stress, especially if the fish are not used to it in the first place.

Placing lots of plants, rocks, and other decorations in the tank beforehand will mean that they will quickly be able to hide till they are able to take a measure of their new environment and adjust accordingly.

Always Try to Add Multiple Fish Together

If you already have fish in the aquarium, it will make a lot of sense to add more than a single fish at a time. This will help ensure that the fish already present in the tank will easily get used to all of the new additions.

It will also prevent a lone fish from getting bullied by the other fish because the existing fish will be able to bond and make multiple new friends simultaneously. It is always better to introduce several new fish in small batches that consist of 2 to 4 fish. This way, you won’t flood your water tank with new arrivals.

It is also important to carefully check the fish before making a purchase. If the fish looks diseased and has scales that seem to be flaking off, it is a good idea to avoid that tank altogether in case it has a contagious disease. You should also make it a point of monitoring your new arrivals for at least a couple of weeks to see if they are able to gel into the environment of your fish tank.

If they exhibit any signs of disease, it is a good idea to isolate them until you are sure that they are healthy enough. This step will help to protect the other fish in the tank.

If you have a spare water tank, you might as well place your new fish there. Leave them for a couple of weeks and check and see if they are healthy and disease-free. After that, you can place them in your original aquarium.

Making the Transfer from the Bag to the Tank

Now that all the preparations are complete, it is time to make the move from their temporary home to their new one. Since you cannot use the store’s water, you have to use a net to pick them up and transfer them into the tank.

Do this very gently so that the fish does not get the time to react. However, be sure to do this only after the fish have been lying in the tank but in their water container for at least half an hour.


Now that you know the answer to the question ‘how I introduce new fish to my aquarium,’ you can just sit back and relax and enjoy the latest additions to your fish family!

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