Whether you have livestock shipped directly to your door or purchase your pets from the local fish store, it is important that any new life you intend to put into your aquarium be properly acclimated first.

Proper acclimation actually helps reduce the stress animals face after relocation. In fact, the acclimation procedure itself is fairly simple—although it does vary slightly for different species of animals. Sensitive fish, corals and invertebrates, such as snails, crabs and shrimp take longer to acclimate than hardier fish, corals and inverts.

In this article, we will cover some of the ways to properly acclimate animals to an aquarium and provide you with some tips and product recommendations along the way.

Checklist of Items Needed for Proper Acclimation

The following three parameters play such significant role in the well-being of new livestock that we'll go over them, one-by-one, to explain why each is important and how it impacts the health of your animal(s).


The temperature inside the package or bag your livestock arrives in is undoubtedly different than the temperature inside your aquarium. Properly acclimating livestock helps to equalize the different water temperatures and can significantly reduce the stress on your new animal(s).



It is also likely the water inside the bag/package your new livestock arrived in has a different salinity than the water inside your aquarium. Beware: sudden changes in salinity can shock fish and inverts and may leave them more susceptible to infection and/or disease. We recommend a salinity of 1.019-1.023 for fish-only (FO) systems and a slightly higher salinity—1.024-1.026—for reef aquariums.

pH and Ammonia

The natural metabolic processes of fish and corals releases toxic ammonia and carbon dioxide during shipping, lowering the pH of the water. At lower ranges, harmful ammonia is transformed into an inter-form ammonium. If the pH were suddenly raised, the ammonium would release ammonia harmful to animals. Proper acclimation will raise the pH slowly, safely releasing and removing ammonia. Keep in mind too that while this occurs more frequently during shipment of livestock, it also occurs while transporting new animals home from your local fish store, albeit not as extreme.

Fish should be quarantined for a minimum of 14 days before introducing them into a display tank. Quarantining inverts and corals is also advised to avoid introducing pests and disease into your display tank. Inverts and corals should be quarantined separately from fish so you can easily observe specimens and inspect for parasites.

If you're looking for specific information about quarantine tanks/systems, please read Quarantine MethodologyHow to Setup a Quarantine Tank or contact us directly to speak with our tech support staff.

Acclimation Methods

Float Method

This method is most useful for most fish and invertebrates:

  1. Switch off the quarantine tank or aquarium lighting and dim the lights in room.
  2. Open the box and inspect the bags to ensure that all animals have arrived in good health and that all the bags have arrived intact.
  3. Float the bags in aquarium for 20-25 minutes to allow the temperature to equilibrate. DO NOT open bag at this time.
  4. Open the bags and roll down the edges 1-2 inches to make the bag stable, and to keep it afloat in the tank. You may also use a clip or a clothespin to anchor the bag firmly against the edge of the aquarium.
  5. Add a quarter cup of aquarium water to the shipping bag. Make sure to keep water from the bag from spilling over into the aquarium. If you need to remove some of the water from the bag to aid in keeping the bag afloat you may do so. Do not dump the water from the bag into the tank; dump it into a bucket or down the drain.
  6. Repeat Step 5 every 3-7 minutes until the bag is full of water. This should take about 30-45 minutes.
  7. Discard half of the water and continue to repeat step 5 until the bag is full once again. This should take another 30-45 minutes.
  8. Compare the salinity of the water in the bag to the water in the tank. If they are the same proceed to step 9. If they are different repeat step 5 until the salt levels are the same.
  9. Remove the animal from bag and place them into the aquarium or quarantine tank (preferable). For hardy fish and motile invertebrates, use a soft net to do so. For tangs, or other sensitive animals, capture them with a cup, pouring as little of the bag's water into your tank as possible. For sessile invertebrates, such as corals or anemones, you may remove them by hand. Be sure to use clean, sterile, and powder-free gloves.
  10. Discard the remaining water.

Drip Method

This is the most desirable method to acclimate sensitive animals to the aquarium but can be used for any fish, coral or invertebrate (many people use this method for acclimating all their livestock). It should be noted that unless you are sure that the water contained in each bag is from the same source you will want a separate holding container for each bag (you can run multiple drip lines to each container). Also if you are going to be using this method, please be present during the entire procedure to prevent spillage.

  1. Follow steps 1-3 from the Float Method above.
  2. Remove the bags from the water and open them. Gently pour the specimen into a holding container. Sterile plastic tubs or buckets work well in this application.
  3. Use airline tubing or the Innovative Marine AuqaGadget AccuDrip Acclimator to set up a siphon from your main tank to the holding container (You can also use an item like the Reef Gently AccliMate or the CPR First A.I.D. Isolation / Quarantine Tank for a simple all in one acclimation tool). If you are using airline tubing you can tie a knot in the line to control the flow (see step 5 for flow rate).
  4. Start siphon by sucking on the free end of the airline tubing, or by forcing water into the tube using any existing pump or powerhead in the aquarium.
  5. Adjust flow to 1-4 drips per second. Innovative Marine recommends 1-2 drips per second for snails, shrimps, crabs, starfish and anemones; 2-3 drips per second for wrasses, puffers, anthias, gobies and butterflies; 2-4 drips per second for most other fish such as angels, tangs or corals.
  6. Once the volume has doubled in about 45-60 minutes, discard half of the container's water, and resume dripping for another 45-60 minutes or until the water volume doubles once again.
  7. Compare the salt levels in the container to the tank and if they are the same go on to step 8. If they are different go back and repeat step 6 until the salt levels are the same. You may also repeat step 6 for extra sensitive animals.
  8. Remove the animal from container and place them into the aquarium or quarantine tank. For motile invertebrates, use a net to do so. For sessile invertebrates, such as corals or anemones, you may remove them by hand. Be sure to use clean, sterile and powder-free gloves.
  9. Discard the remaining water.

Reef Gently's AccliMate Method

Few things in this hobby are as simple, safe and effective as acclimating new livestock using the Reef Gently AccliMate. The AccliMate comes in two sizes to accommodate most livestock that you will encounter and its usefulness as an aquarium multi-tool goes far beyond just acclimation.

Here is the acclimation process in a nutshell using the AccliMate's automated Continuous Exchange System (CES).

  1. Secure the AccliMate to the outside of your aquarium or quarantine tank with the included Iron Grip suction cups.
  2. Place your livestock with the fish store water into the AccliMate.
  3. Using the included tubing, start a siphon from your tank into the AccliMate.
  4. Using the included drain tube and precision metering valve, adjust the outflow from the AccliMate into a waste water container. The drip rate can be adjusted to accommodate various species with different levels of sensitivity.
  5. Walk away.
  6. Come back when the automatic acclimation process is complete and release your livestock into the tank without nets by using the AccliMate's patent-pending release system.

Other Tips

  1. Take your time and be patient.
  2. Keep plenty of new salt water on hand to maintain your water level in your quarantine tank or aquarium during the acclimation process.
  3. If any animal is without water, introduce it immediately into the quarantine tank or aquarium. Many invertebrates are inter-tidal, and are accustomed to periods of little to no water.
  4. If an animal arrives and looks dead, acclimate it anyway. Many animals will make a quick and dramatic recovery when properly acclimated.

The animals we keep in our tanks go through quite a bit before they get comfortable in our home aquariums. Most marine species are collected in the wild and go in-and-out of multiple holding tanks and bags before ever arriving in our hands. This all puts a tremendous amount of stress on animals, so anything we can do to minimize that stress before introducing them to our aquariums will help their overall health and well-being. Of course, proper acclimation is just one of many things we can do to make the transition easier. However, if you take the time to acclimate new additions properly, you will likely be rewarded with a happy and healthy specimen.