Fish Acclimation

It’s all very exciting when we finally get our new fish home and just want to put them straight into the tank!

Most new fish keepers will bring home their fish, float the bag and then dump everything into their home aquarium (water, fish and all). This is a poor way to acclimate your fish and will more than likely result in fish shock and death.


A part from the fish being shocked by water parameters and temperature change, you risk adding any diseases or parasites that would potentially be in the store water.

This is always heartbreaking after purchasing your new fish, and some can be very quick to assume the store had poor health fish, when in fact this fish shock death can be prevented through proper acclimation.

In order to give your fish the best introduction to their new environment (and to minimise fish loss) we recommend following a few tips to help their adjustment.

We will touch base on the basics of acclimation, and also discuss some tips for more sensitive fish through drip acclimation.

Let’s dive in!

Acclimation is the process of introducing new fish and invertebrate into your aquarium with the aim to minimise shock (which could kill your new friends)

Acclimation can start before you even leave the local fish store. You could ask what their water parameters are to have a good idea of how different it will be to yours at home (The big differences here would be water PH levels, and water temperature).

Hot tip: You could pick up a water testing kit, and test their water yourself from the fish bag, and compare it to your tank at home. Pick one up from Nick’s here:

Now that you are home with your new fish, it is time to acclimate them into your aquarium. We do recommend heading straight home after purchasing your fish, to start the acclimation process as soon as possible.

Step 1:  Dim the lights & Open the bag

Before floating the bag, it’s usually a good idea to turn down/off the lights to prevent shock for your new pet. You can then remove the rubber band and begin floating the bag.

Hot tip: If you roll the top of the bag down a few times over itself, the bag will float on it’s own without tipping over. If you find it still tips to the side, try rolling it down a little more. Be mindful of fish who may jump out (such as Bettas).

Step 2: Testing the water, and adding it to the bag

Prior to purchasing your fish, your tank should be fully cycled and you should be aware of how your tank water parameters are. However, it would be beneficial to check again before physically adding your fish into the aquarium.

If you have a water testing kit, this is where you could test the water parameters from the store fish bag and compare to your tank. This should give you a good indication of where the pH levels are, and how drastic the change may be.
There will likely be some ammonia in the bag from the travel, you could always add some water conditioner (like prime), Amguard or some API Stress Coat.

You can then begin adding water from your aquarium into the bag (1/2 cup every 15 minutes). This slow process is necessary to ensure the fish acclimatize to the change in pH, temperature, nutrient levels, salinity, sounds, lighting and oxygen content. You may need to repeat this until the temperature and pH levels are similar. If you have a delicate species (such as shrimp or discus) we recommend drip acclimation which may take a little longer. We will touch base on this below.

Note: It’s a good idea to keep your water testing kit close by and monitor the water parameters over the next few days. Adding new fish into your aquarium will increase the bioload on your filter system, and your beneficial bacteria will be building up on the biofilter to remove additional ammonia waste. This is why it’s recommended to only add a small handful of new fish at a time.

Step 3: Adding your fish to the aquarium

Once the pH and temperature are similar in the bag to what they are in your aquarium, you may remove the fish from the bag with a fish net and add them into the tank taking caution not to get their fins caught in the net. Remember to try avoid adding the bag water into your aquarium.

When it comes to more sensitive fish such as exotic, rare, wild caught, rams, discus or even shrimp, it’s imperative to ensure we prepare them for their new environment the right way.

Drip acclimation is a longer process, however is preferred by most hobbyists for all their fish acclimating. This process usually takes anywhere between 30 – 60 minutes, and only really requires 2 x material products.

The Materials:
1. A small container or bucket (You may also use the fish bag they’re in)
2. Airline tubing
3. Air Control Valve

The Method:
1. Start by emptying both your water and fish into a small container/bucket (you may also choose to keep them within the bag they’re already in).
2. Attach one piece of airline tubing to one part of the valve and into your aquarium, and the other piece of airline tubing to the second line of the valve. Ensure your valve dial is wide open.
3. Begin siphoning the water by sucking on the end that will go into the bag (being cautious not to swollow any tank water, this is a very quick suck and remove).
4. Adjust the valve dial until you have dripping of about 4 – 5 drops per second into the fish container. You will want to keep this dripping until the water volume has doubled. You may choose to then empty half the water and repeat.
5. Once the water has doubled, you may begin to follow the remaining steps of acclimation (dim lights, feed aquarium fish to keep them busy, use a net to carefully add them to your aquarium and monitor). If you are quarantining, you will do all these steps with your quarantine tank water, and then again in 2 – 4 weeks times from the quarantine tank to your aquarium.