How To Acclimate Saltwater Fish (Best Methods)

Image Credit: Tara Halstead via
Image Credit: Tara Halstead via

How To Acclimate Saltwater Fish (Best Methods)


Your saltwater aquarium is finally all set up and you are ready for your first fish to be introduced to the tank. You can’t just throw the fish right into the water though. Your fish needs to acclimate to its new saltwater aquarium. How do you do this? Follow the steps below to ensure that your fish has a healthy and safe acclimation.

Tools For Acclimating New Saltwater Fish To Your Tank

Drip Acclimator

Drip acclimation is the best method of introducing new fish to your aquarium.

Hang On Container

An indispensable tool for acclimation and many other aquarium tasks.

Bag Acclimator

A great tool for acclimating new fish right in the bag that they were delivered to you in.

Stress Relief

Transporting fish is stressful for them. Stress relief will help increase their health.

What Does it Mean to Acclimate Your Fish?

Fish are very particular about their living environment. If you throw your fish directly into your curated saltwater tank too quickly, you run the risk of shocking your new fish. Your tank probably doesn’t match the same parameters as the tank that was previously housing your new fish.

Fish need time to adjust to changes in the water like water temperature, ph, and salinity. By taking the time to acclimate your fish, you guarantee that the fish is receiving as little shock to their system as possible. This helps to reduce stress and keep your fish happy and healthy.

Acclimating Shipped Fish

If you bought your marine fish online, the room where you first open the box containing the new fish should be dark. The fish have just spent their entire transit in darkness and throwing open their box in a well-lit room will come as a shock to their systems.

Instead, open the box from the side and let a little light into the box. The fish will slowly begin to get used to that little bit of light and then you can more safely remove the fish from the box.

Steps Before Acclimating Your Fish

If you bought your fish online, the room where you first open the box containing the new fish should be dark. The fish have just spent their entire transit in darkness and throwing open their box in a well-lit room will come as a shock to their systems. Acclimating to the light in the room can take anywhere from 5-10 minutes.

Don’t throw the bags into your aquarium just yet, you should check your saltwater aquarium’s salinity and temperature. If the water reads a comfortable salinity of 1.020 – 1.026 or 27- 35 PPT and your temperature range is between 76 and 80F, you are ready to go.

make sure to properly rinse and clean any acclimation container you may want to use.

What You Need Before Acclimating Fish

Gathering the materials now will prevent confusion and delay when acclimating your saltwater fish. If this is your first time, the materials you gather now I recommend you keep together for whenever you get new fish. This will cut down on time in the future and ensure that you are always prepared for transferring your fish.

Fish Acclimation Kit

Fish acclimation kits are also available for purchase. If you are not interested in DIY, you can buy a premade drip line that has a flow regulator already installed on it. The kits are relatively inexpensive and could save you a little bit of time from learning how to make the hose yourself.

Popular Fish Acclimation Methods and Supplies

The two most common (and trustworthy acclimation methods) are the float method and the drip method. You will want to select the method that works best for you and the type of creature that you are trying to acclimate to. The float method is better for fish while the drip method is better for heavier creatures like invertebrates and coral. A reminder that with all of these acclimation processes that the time shouldn’t take longer than one hour. The longer you take to complete the acclimation process the colder the acclimation containers can become.

Float Method

The float method is most common for fish when trying to get them acclimated to their new aquarium life. Careful not to allow any of the bag water into your aquarium.

  1. Lighting
    Lower the lights in the room and turn of your aquarium lights. You will want to make sure to follow this step to prevent any undue stress to your new fish.
  2. Floating
    Float the sealed fish bag carefully in the aquarium for 15 minutes. The bag should not be opened at this stage. You are trying to have the temperature of the water in the bag slowly match the temperature of the aquarium water. Just like the lights, we want to try to mitigate the levels of change for the fish.
  3. Opening
    After the 15 minutes are up, you can cut and open the bag. Roll the sides of the top of the bag down an inch or so to help create some buoyancy and help the bag continue to float on the surface of the aquarium.
  4. Refreshing
    You should add about a half cup of aquarium water to the bag now every five minutes until the bag is full.
  5. Removing
    Once the bag is full, take the shipping bag out of the water and remove about half the water that is in the bag. The water that you dispose of should not go back into your aquarium, instead, the bag water goes directly in the drain. To resume moving the bag too much, use a small jug to help empty the bag.
  6. Repeating
    Repeat this process (steps 4 and 5) for about 30 minutes.
  7. Testing
    Once you believe you have changed the water enough, test the water, and if it the same as the water in your saltwater tank, the fish can be placed carefully within your tank.

The Drip Method

This method is much more involved than the float method, but this acclimation process is especially good for the heavier inhabitants of your aquarium including corals, sea stars, and wrasses. You will need the following items for this method: 3 to 5-gallon bucket (acclimation container), 3ft of airline tubing, scissors, and a clothes peg.

  1. Follow steps 1 and 2 from the float method.
  2. As you wait for the fifteen minutes, double-check that you cleaned and rinsed your bucket and other tools that will be coming in contact with the aquarium water or your fish.
  3. Carefully cut open and empty the transport bags into the bucket within the vicinity of your aquarium. If you are acclimating invertebrates, ensure that they do not become exposed to the air. They should always remain in the water. You may need to tilt the bucket to sully cover your creatures.
  4. Grab the airline tubing and create a siphon running from the aquarium to each bucket that you may be using. You will either need to buy a control valve to regulate the flow or you can tie knots in the tubing to control the drip line. I recommend securing the tubing in place with a clothespin or other easy to remove holder. This will help prevent the drip line from sliding all over the place. You are ready to start the drip acclimation.
  5. Create a siphon by sucking on the end of the tubing that will be placed in the buckets. Once the water begins to flow, slow the flow to about 2-4 drips per second by tightening the knots that you made. Make sure to monitor the drip carefully.
  6. Now just like with the float method, you want to wait until the bucket water levels double. Once this happens, carefully remove half the water and start again. Make sure to discard the water down the drain.
  7. Check the salinity and temperature of the bucket water. Once it matches the salinity and temperature of the aquarium, you can begin to transfer your fish into their new environment.
  8. REMINDER: invertebrates like sponges and clams should not be exposed to air. Use a clean specimen bag to transfer these animals to the aquarium safely. Invertebrates are also sensitive to specific gravity. You will want to test for specific gravity with a hydrometer. The reading should be between 1.023 and 1.025 to prevent severe stress to the invertebrate.

How to Transport Saltwater Fish

You have just bought your new fish, but you need to pick it up from the store. How do you guarantee safe travel for your new saltwater fish? You should bring some sort of container, like a box or bucket, in your car to place the fish. The container will help prevent the fish from rolling around too much as you drive home.

The container should be located somewhere secure and I recommend where you can see it. You don’t want any mishaps taking place before you can bring your new saltwater fish home.

Is Fish Quarantine Needed?

Quarantining your fish is not required but you are running an unnecessary risk if you just begin to acclimate your fish. By quarantine, you are making sure that you are only letting specimens into your saltwater aquarium that are safe. The last thing you want is for one sick fish cause a whole slew of issues for your entire aquarium.

To quarantine a fish, you need to have a second aquarium available. Since you are only quarantining the fish, the second quarantine tank does not need to be anything fancy. It only needs to be able to house the fish for about a 6-week period.

Remember that whenever a fish moves to a new container, they should be acclimated to it. Please follow the methods listed below for acclimating your fish, whether that is to your main saltwater tank or a temporary quarantine tank.


Now you have all the information you need to safely acclimate your new fish to their new saltwater aquarium home. If you are patient and careful with the acclimation process, you should have no trouble transferring your saltwater fish into your aquarium.

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