After setting up your fish tank, you may be wondering what is the best way to add your fish to your aquarium. There are several different ways of acclimating new fish to an aquarium.

But some of those fish acclimating practices can be deadly for your fish. So, let’s find out the best way to add your fish and why it’s beneficial to do the fish acclimation in that way. We will talk about the scientific background and underline water chemistry. 

Why do you need to acclimate fish before releasing them into Aquarium?

Adding fish into your aquarium seems pretty simple. But it can be somewhat stressful for the fish. Especially if you get your fish online, it will spend an entire day in a bag with a dark box. 

Aquarium fish delivery box
Aquarium fish delivery box

As well as, if it’s in a colder climate, the water temperature in the bag can go down. So if you add the fish directly into the tank, the sudden temperature difference can cause to stress out your fish. 

When fish are stressed, their immune system becomes compromised, and fish are more prone to disease. So we want to make this process very simple and stress-free for the fish, and that’s why acclimation is needed. 

Different Practices of Acclimating Fish

The first step of the fish acclimating process is to balance out the temperature. For that, we can use drip acclimation or the floating method. Also, switching off the aquarium lights during the acclimation process is recommended. It helps to keep your fish calm and stress-free.

Drip Acclimation method

Drip acclimation is one of the methods that many fishkeepers follow to add new fish to their aquariums. 

First, we slowly mix the water from our tank into the fish bag and acclimate the temperature. After that, we can add the fish into the tank without mixing the fish bag water with our aquarium. For that, we can simply use an aquarium net or hand. 

Plop and Drop (Floating) Method

Floating method of acclimating fish
Floating method to acclimate fish

Plop and drop acclimation means first we let the fish bag float in the aquarium water. When floating, the water in the bag gets slowly balanced with the temperature in your tank. This may take up to 20 -30 minutes. 

Once the temperature in the bag is the same as in your tank, you can add fish to the tank. Here also, we should not add the fish bag water into the aquarium.

What is the best way of acclimating Fish to a new Aquarium?

Both floating and drip acclimation methods can be used to add your fish into a new tank depending on the situation. 

When considering the drip acclimation method, it takes somewhat less time to balance the water temperatures because you can easily and quickly match the bag temperature with the tank by mixing water. 

So it is a good method if you need to shift the fish immediately due to lack of oxygen or any other reasons. But there are some constraints. The scientific reasons behind those constraints are as below.

When fish are placed in a bag, they will release two different waste products. One is Ammonia, which can be very toxic to fish. The other thing is CO2, which can convert into Carbonic acid. With this Carbonic Acid, Ammonia becomes less toxic to fish.

But when you drip water into the bag, Carbonic Acid gets distilled, and Ammonia toxicity becomes prominent. So it can harm the fish, as they are already stressed due to long transport.

So many experienced fishkeepers recommend using the floating method to acclimate the temperatures though it takes more time than the drip method.

Why should you avoid mixing fish bag water with the Aquarium?

We should never mix the fish bag water into the aquarium. Because there could be harmful waste products, or water itself could be harboring some kind of fish disease. We should carefully take the fish out and slowly add them to the tank.

Adding fish with an aquarium net
Adding fish with an aquarium net

Now you might be thinking that, can`t the fish itself be a carrier for harmful diseases? Surely it can be possible. That’s why we need to quarantine fish before adding them into a stabilized aquarium.

How do you quarantine a new fish?

Quarantining new fish is very important before adding them to your main tank. Because your new fish might have a certain disease though they don`t show any systems at first.

There is a high risk of your new fish getting infected during their transition from wherever they were captured or bred to your tank. They are stressed during this transition, and they can catch many diseases.

You should keep a separate tank to quarantine your fish. If you don`t have additional tanks, you can simply make a DIY Quarantine tank for your fish. 

Quarantine tank
Quarantine tank

It’s better to cycle your quarantine tank too. If it is not cycled properly, you need to do tank maintenance and 50% water changes regularly to avoid accumulating toxic substances in the tank. You want to keep your tank as clean as possible during your quarantine process. 

It`s recommended to avoid feeding too much. All the excess food you leave in your quarantine will only damage the parameters, spike your ammonia, and make the water unhealthy for your fish. You want them to be in the least stressful environment possible, and obviously, you want to keep an eye on them.

How long should I quarantine new fish?

Normally, it is recommended to quarantine your fish for two weeks. In this quarantine period, you should observe closely whether they show any symptoms of diseases. If you notice any sign of disease, you should take immediate action to treat that disease.

Should you medicate the quarantine tank?

Aquarium fish with itchy skin
Aquarium fish with itchy skin

You can use general medications to treat your fish if they are not in severe disease. But you should take veterinary advice when treating critical diseases. Normally we can use aquarium salt without a veterinarian’s perception, and it can react against many minor diseases. 

Another product that can be recommended is Stress Guard supplements. Stress Guard is a very good product used to reduce the stress in your fish, especially when adding new fish to a new tank or new quarantine in a new environment. This stuff comes in handy, and it also promotes healing.

As well as, don`t add any disease treatment unless you see symptoms. All medications add stress to your fish, so if it’s not needed, don`t add it. Your fish are already at a high-stress level. Their stress levels are the most important thing right now, and adding unnecessary medication will just elevate those stress levels.

Besides disease, another reason why you want to quarantine is just to check your fish’s physical condition. How battered did they get to you? Do they look extra stressed? Do they need a little healing time before going into the main tank? 

So another thing you want to watch for during quarantine is how your fish are eating. If they are active and eating properly, it is a sign of good health.


Acclimating Fish to the Aquarium

Acclimating fish into your new aquarium shouldn’t be a big deal. It’s not a process that should take hours and hours, and you can do it without completely stressing your fish out.

So to conclude, the overall opinion on this hobby is that you should quarantine your new fish both for the safety of your established tank and the well-being of your new fish. 


I am Prasanjaya who is an aquarium hobbyist for nearly a decade. I wish to help fishkeepers to get accurate and helpful information regarding every aspect of fishkeeping.

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