Acclimating your fish is the process in which you get your new fish accustomed to the water chemistry in your quarantine or isolation tank. You always have to presume the water you have in both your display tank and your quarantine is going to vary in some way from the water in which the fished previously housed or shipped in. Regardless of whether you bought it online or purchased from a local store, the pH, temperature, salinity, and even nutrient levels will be different from the levels in your tank.

If you were to immediately transfer the fish from the bag into your QT tank, without any sort of acclimation, the fish will stress further increasing the chances of a problem.  You also never want to allow the "bag water" into your QT tank or display, at least do everything you possibly can to minimize the transfer of that water.  This "bag water" could possibly contain pathogens or medications you just don't want to transfer into your QT.

We reference the Quarantine Tank in this video/article because responsible tank owners always set up and use a separate QT tank. All new fish coming home will go into the QT system first because acclimating a new fish directly into your display aquarium is just risky business for a variety of reasons. When the time comes to add fish from your QT tank into the display, the same exact drip acclimation process can be followed.

What Is Drip Acclimation?

There are a few different ways to acclimate aquarium animals. You should choose the procedure according to the type of animal - fish, coral, or invertebrate. This article specifically outlines the Drip Acclimation process for saltwater fish which is the most widely trusted method of acclimation.  We will cover acclimation procedures for corals and invertebrates in a later episode.

Should I Acclimate?

Yes, acclimation is your best route for ensuring a successful and safe transfer of live fish into your QT tank or display. While a small minority of hobbyists might argue against drip acclimation specifically, it is the most widely used and successful method of acclimation.

How To Drip Acclimate Saltwater Fish

Essential Equipment

  • Scissors
  • Buckets
  • Drip acclimation tube or small cup
  • Towel
  • Clean seawater (no more than 5 gallons)

1. Inspect The Fish

This only applies to fish purchased online or that have undergone some long journey, like an overnight car ride in a box.

First, dim the lights in the room and on your QT tank, this will reduce stress and avoid shock from sudden light changes when opening the box. Make a mental note of the condition of the box and as well as the temperature inside.  Inspect each bag carefully, ensuring all of the fish are alive. Should a fish arrive DOA, report immediately with the retailer if they offer a Live Arrival Guarantee. Reporting right away is mandatory in these scenarios.

2. Temperature Acclimation

Float the bags in your tank which allows the water temperatures to equalize. Let them float for at least 20 minutes, sometimes longer if you feel the bag water was really cold and needs more time. Never open the bags during this process.

Pro Tip: Be aware the bags can block your overflow weir or surface skimmer, be sure to keep the bags clear of your overflow while floating.

3. Empty Bags And Water Into A Bucket

One at a time, remove the bags from your tank and empty them into a bucket. Be sure you're holding the bag securely inside the bucket before you cut it open, gently pour out the fish and water. 

The bucket needs to be small enough so that the fish stays submerged. The bags won't contain a ton of water so if you have to, you can tilt the bucket on its side so all the water flows to one corner or edge while you're emptying the bags. 

4. Start Drip Acclimation

There are two approaches to drip acclimation which accomplish the same thing; essentially the slow transfer of tank water into the bucket containing your fish.  You can either use a small siphon tube or simply transfer the water manually using a small cup.

Small Siphon Method - You will need 4 - 6ft of small diameter flexible tubing, airline tubing or small diameter silicone tubing works fine. You also need a small valve to adjust the water flow.  Alternatively, you can just buy the AccuDrip kit (less than $10) from Innovative Marine which comes with everything you need including a rigid U-tube to secure the tubing on your tank and a bulb pump to start the siphon. <<Highly Recommended

Secure one end of the tubing on your tank, being sure the end of the tube is underwater. Place the other end of the tube into your bucket and then start a siphon. Once the water begins to flow, dial back the flow to a slow drip using the valve. You want to be moving roughly 2-4 drops of water per second. You can even tie loose overhand knots in the airline tubing to slow down the flow should you need to.

Cup Transfer Method - Manually transfer 1/2 cup of tank water every 5 minutes into the bucket.

Watch Video: 5 Ways to Start a Siphon for an Aquarium Water Change - Beginner's Guide Ep: 24

5. Remove Half Of The Bucket Water

Once the water volume in your bucket has doubled, you want to remove half of the water and dispose of it down the drain. Continue with your siphon/water transfer and let the bucket water volume double again.

6. Stop Siphon

After you have doubled that water volume twice, stop the siphon. The entire process should take about 20-45 minutes depending on your exact drip-rate.

7. Transfer The Fish Into Your QT

Be careful not to add any significant amount of bucket water into your QT and transfer the fish.  You can scoop the fish up with a net, use your hand, or even a small cup. Safely dispose of the bucket water down the drain after all fish have been transferred

Pro Tips: Don't use your hand if the fish is poisonous. Fish fins, gills, or spines can get caught in a net, free them carefully with your hands or cut the net, don't just shake the net. Do everything you can to minimize the amount of water you transfer from the bucket to the QT tank. 

8.  Add Clean Seawater

Since the water was removed from your QT, you should fill it back up with some clean seawater.  Never pour the remaining bucket water into your tank.

9. Wait To Turn The Lights On

Don't turn the lights on until the following day. Give the fish some time to adjust and acclimate to the new environment before returning to your regular light schedule.