When introducing new fish to a tank, it is critical that they first be acclimated to the water to avoid inducing shock that may injure or kill your fish. The aquarium acclimation process is delicate and can be somewhat tedious, but if done correctly, it results in healthy, happy fish that bring new life to your aquarium

Why do we acclimate fish?

While fish and other aquatic creatures tend to be highly resilient, a significant change in water parameters will cause shock to your fish. As a result, your fish may act oddly or even go belly up if the parameters of your tank water are too dissimilar to those they are accustomed to.

• Temperature

Most fish are susceptible to significant increases or decreases in the water temperature in which they are housed. To ensure their safety, ensure your aquarium water is the correct temperature for any fish species you plan to introduce. 

The temperature of the water housing the fish should be brought to equal that of the new aquarium before the fish can be safely released

sudden change in temperature can cause shock to fish, one of the most common causes of death for fish introduced to new tanks.

• Change in Water Parameters

Hardness, alkalinity, pH, ammonia, and many other water quality factors can significantly affect the health and survival of your new fish. 

To ensure a safe transfer, the fish must first be slowly acclimated to the parameters of the tank and only then released

• Waterborne Disease

Water from fish sellers and aquarists can contain unknown diseases or parasites that can impact the health of your aquarium. To ensure the safety of anything already in the aquarium, ensure that any water with your new fish is discarded appropriately and not poured into the tank.

Additionally, to ensure that your new fish are not sick or affected by something that could damage your aquarium, I recommend that you quarantine them before putting them in. Depending on the health of the fish, this process can take anywhere from a few days to two weeks. 

Quarantining is not necessary, per se, but it can save you a headache later

And now for the acclimation process.

Method 1. 

1. Float the bag

Place the bag (Or whatever else your fish is in) in the aquarium, ensuring it is well sealed so no water can get in or out. The bag should float on the surface.

Be careful that the bag doesn’t get too close to any lights or heating elements, as this can heat their water and cause harm to your fish. 

Please turn off any aquarium lights, as these can cause additional unnecessary stress to your fish while they are floating on the surface

As your fish acclimate to the temperature of your aquarium, be careful to observe them closely for abnormalities. These can include color changes, absence of interest, or the fish may appear to be breathing rapidly. 

If you notice any of these changes, remove the bag from your tank and check to ensure that the water temperature is within a safe range for your fish. 

After approximately 20 minutes, the bag's temperature should be equal to that inside the tank, and it can be removed from the aquarium.

2. Add Aquarium Water

Now that your fish have been acclimated to the temperature of your aquarium, we will begin acclimating them to the other water parameters.

Before purchasing any fish, you should test your water to ensure that it is safe for them. Different species require varying water hardness, pH, ammonia levels, nitrate and nitrate levels, and much more. If the water you intend to use does not match the required parameters of your fish, they will likely be unhealthy or die.

Once you are sure that your tank parameters are correct, you can begin adding aquarium water.

Pour your fish with their water into a container, ensuring enough water to cover the fish entirely. Next, you will add water from your aquarium. This should equal roughly 50% of the total volume of water already in the container

After roughly 10 minutes, empty half of the water from the vessel containing your fish. 

Repeat this process until there is little to none of the original water left in the fish container (Approximately 3-4 times)

You can now release your fish into the aquarium. Use a net or other object to place them directly in the aquarium water. Do not dump the water from their container into your aquarium; it can lead to disease or infestation.

• Be careful that the water in your fish container does not cool off while you acclimate the fish. This will cause additional stress when the fish is introduced, negating the effect of floating the bag.

Method 2. The Drip Method

PLEASE NOTE: While this method is a highly effective way to acclimate fish, it can only be conducted on fish that have been contained for a maximum of 3-4 hours

During transportation, fish take up oxygen and release carbon dioxide due to the excretions created by the fish; ammonia levels in the bag increase. As this happens, carbon dioxide levels also increase, lowering the pH of the water. This ensures that the ammonia in the bag remains nontoxic. 

However, once the bag is opened, carbon dioxide is released, allowing oxygen in and increasing pH levels. This, in turn, causes the ammonia, which had previously not been dangerous, to become toxic to the fish. 

Being left in this state can damage the fish's gills. Therefore, it is better to use method one for any fish that have spent a long time in transit, as it will reduce their exposure to these harmful chemicals.

• Process

The drip method is highly effective for acclimating sensitive fish and invertebrates to your tank.

For this process, you will need a clean bucket, an airline hose, and something to squeeze or restrict the airline hose.

1. Introduce fish

Pour the fish and their water into a clean bucket. Ensure that the bucket is close to, and preferably below your fish tank to aid with the siphoning process.

Make sure that the fish are completely submerged.

2. Siphon

Take your length of air hose and utilize a band, valve, clip, or other device to restrict the pipe so that the hole can only accommodate roughly 3-4 drops of water per second.

If you are not comfortable with this part of the process, you can buy drip siphons here.

Next, draw water into the hose so that it begins to siphon water from your aquarium. 

The tiny amount of water allowed through your siphon should be enough to acclimate your fish to water temperature and all other parameters.

3. Water Change

Once the water in your acclimation tank has doubled, dump out half of it and re-commence your siphoning. At this point, the water should be half from the tank and half from the acclimation tank.

Repeat this process 2-3 times until most of the water in the acclimation tank is from the aquarium. 

This process can be lengthy for larger fish that require more water, so be sure to utilize a heater if the dripped water is not enough for temperature acclimation.

4. Move Your Fish

Your fish are ready to be moved into their new tank. Gently place them in the tank with a net or other object, being careful not to dump any potentially contaminated water in with them.

5. Enjoy!

Fish are awesome! If the acclimation process has been completed correctly, your fish should be healthy and happy in their new tank… Enjoy them!