How To Acclimate Saltwater Fish (Don’t Mess This Up)

Updated Oct 10/2020

Learning How To Acclimate Saltwater Fish

Ok, I’ll admit it. I don’t always acclimate my fish properly before introducing them to the tank. There I said it.

There have been times over the years where I just couldn’t complete a full acclimation process for one reason or another. It’s risky and I’ve been lucky.

I know that’s not the “normal” or “proper” way to do it but I’ll let you in on a little secret about the saltwater aquarium hobby – There is never a 100% foolproof way of doing anything!

Now in saying that, I do recommend you acclimate your fish properly prior to adding them to your tank. It is a safer way than the “plop and drop” method where you open the bag and toss the fish in the tank! Although I have done it without issues.

To be as safe as possible, always quarantine and acclimate new livestock.

Before you start to acclimate your fish, there are a few things you need to know.

Why do you need to acclimate saltwater fish?

Acclimating fish, corals, and invertebrates are important as they are very sensitive to changes in water conditions. The water that they are currently in will be different than your tank water and if they don’t have the proper time to adjust to those changes, they will be stressed and perhaps not survive the change over to the new tank.

Water temperature, PH, salinity, nitrates, are all things that your new fish will need to adjust to.

Acclimating them properly will give them a better chance at a successful transition into their new home.

How Can You Introduce Saltwater Fish To A New Aquarium?

Properly maintaining a saltwater tank will take a lot of time and patience on your part. Whenever you want to introduce a new fish to your tank, you’ll want to take the time to properly acclimate them to this new environment.

You’ll want to start by placing the fish in a quarantine tank. It’s important to make sure that the fish is free of diseases. Even if the fish appear to be healthy, they could have an illness that they could pass along to the other creatures in your tank. Showing a little bit of extra caution could save you a lot of heartbreak.

Quarantine tanks are not difficult to set up and are crucial to avoiding illness and disease from entering your main tank. I recommend a few weeks of quarantine prior to moving the fish to the main tank.

Simple quarantine tank

Steps to take prior to acclimation

Before you begin the acclimation process, there are a few steps you should complete.

  • Make sure the tank lights are off. It’s also a good idea to turn off any bright lights in the room.
  • Do not shine flashlights or any bright light onto the fish bag or inside the box.
  • If your room is bright, open the box slowly to let light in over a few minutes.
  • Make sure you have the necessary tools ready to be used. Scissors, containers, scoop, net, tank clips, are helpful to have on hand.

Once you’re ready to introduce the fish to the aquarium, you have a few different options.

  • Drip acclimation
  • Floating bag acclimation
  • Bucket acclimation

These are a few of your options. You’ll want to learn more about all of these methods so that you can decide which one you would like to use.

What Are Some Of The Methods Of Acclimation?

When you’re learning how to acclimate saltwater fish, you should look at all of the different methods you can use.

Consider the pros and cons of each option so that you can settle on the best method for your fish.

Drip acclimation

Drip Acclimation

This is widely considered to be the safest way to acclimate a new fish to a tank. This method requires you to adjust a fish to the water in a tank drip by drip.

While this method might sound complex, it can be easy as long as you have access to all of the supplies that you need. You can do this by simply taking some airline tubing and tie a knot in it allowing the water to drip out of the main aquarium at a slow rate.

It is recommended to achieve a drip rate of 2 drops per second.

You can also use a drip acclimation kit, which is mentioned below. These are inexpensive and work great.

Drip acclimation takes a while to do but will acclimate the fish the best way.

Floating bag method

It’s more common to use this method when freshwater fish are being acclimated to a tank, but the method can still be used with saltwater fish. This method requires you to open the bag that the fish is in and remove about 25% of the water from it.

You should replace the water that you’ve removed from the water that comes from your tank. Do this with a small amount of water each time.

Continue this every 10 minutes until all of the water in the bag has been replaced.

Once the process has been completed, you can remove the fish from its bag and place it in your tank. This is the fastest way to acclimate a fish to a tank, but it is also one of the riskier methods. If you choose to use this method, you should be aware that you could be exposing the fish in your tank to disease.

Using an acclimation and quarantine box makes life a lot easier! Check them out on Marine Depot here. 

Bucket method

This method is similar to the floating bag method, and it has similar drawbacks. The key difference is that it requires you to float the bag in a bucket rather than in your own aquarium. Since water from the bag won’t be able to leak into your aquarium, this is a slightly safer method.

Pro tip: It’s very important to not let the water from the bag that the fish is in to enter the main tank. 

How Long Do Fish Need To Acclimate?

The amount of time it will take for your fish to acclimate to a new tank will vary based on the method that you use.

Ideally, you should be quarantining a new fish for approximately two to three weeks after purchasing it.

Once the quarantine period is over, you should be able to acclimate the fish to your tank fairly quickly.

The drip acclimation method could take a few hours to complete.

This isn’t a process that you should rush through. It’s best to take things slowly so that you can prevent potential issues.

You might be excited to introduce a new fish to your tank. However, you’ll want to make sure you don’t cause any harm to either the new fish or the fish that you already have in your tank.

How Do You Drip Acclimate? Drip Acclimation Kits

If you do decide to drip acclimate your fish to your tank, you’ll want to make sure you have the supplies that you need. As mentioned earlier, you can use a bucket and a long piece of airline tubing. You’ll want to be sure that both the bucket and the tubing are completely clean.

You should remove the fish from its bag and empty the contents into your bucket. From there, you’ll want to set up the tubing so that new water is entering the bucket one drop at a time. Tie a knot or pinch the tubing to do this.

You can remove some of the old water from the bucket and continue the process until the fish has been completely acclimated to the new water.

If you want to drip applicate fish to your tank, but you are concerned that you don’t have the proper supplies, you should consider purchasing a drip acclimation kit.

The right kit will provide you with everything you need to acclimate a fish to your tank using the drip method. In addition, these kits will provide you with instructions that you’ll be able to follow.

A lot of people are wary of the drip application method, even though it’s the safest way for you to introduce a fish to your tank.

If you have these kinds of concerns, then buying a kit is a smart idea. You’ll get everything you need from your kit, and you’ll be able to follow the instructions to the letter.

How Do You Acclimate Saltwater Invertebrates?

You should be able to follow a similar process when acclimating invertebrates to your tank. As with fish, the drip acclimation method is usually going to be best.

However, you’ll also want to make sure you are temperature acclimating any creatures that you are adding to your tank.

Typically, temperature acclimation shouldn’t take very long; this is something that you should be able to do in about 15 to 20 minutes.

It’s important to make sure that the invertebrate will be completely comfortable with the temperature in your tank.

Use a thermometer so that you can accurately measure the current temperatures in your aquarium. Don’t rely on guesswork; you’ll want to know exactly what the temperature of the water is.

Acclimating fish and invertebrates to your main aquarium is something that you should do. This is the safest way to protect the new fish and other tank mates from disease and stress.

I do favor using the drip acclimation method when possible. It’s easy to do and is best for all involved!

Steps to take after acclimation

Once your acclimation process is complete and your new fish is in the tank, there are a few steps to complete.

  • Leave the lights off for a few hours to give the fish time to adjust.
  • Keep an eye out for any aggression as it’s possible for new tankmates to be bullied.
  • Your new fish may not eat right away, but make sure they eat somewhat soon after being added.
  • New fish may also hide for a while, so keep an eye on them to ensure they are active and swimming.

Important Acclimation Tips

  • Never rush the acclimation time and be patient.
  • If the fish doesn’t look to be 100% healthy, still complete the acclimation process.
  • Do not use air stones in the shipping bag. This will increase the PH and ammonia levels of the water in the bag to dangerous levels.
  • Once the fish is in the tank, leave the lights off for a few hours.
  • Invertebrates can be more sensitive than fish, ensure proper salinity before adding them to the tank.
  • Certain fish, coral, inverts, can’t be exposed to air. Do not use a net to remove them from the bag.

How long does it take for fish to adjust to salinity differences?

Hopefully, your new fish will come from a tank where the salinity level is close to yours. This will allow for an easier transition and it won’t take as long for the salinity to balance out during acclimation.

If the salinity in your tank is 1.025 and the store tank water is 1.023, it won’t take long to equal out.

You can expect it to take around 30 minutes. Sometimes longer if the salinity difference is greater.


Acclimating your new fish is an important part of fish keeping. Learning how to do it properly will ensure your new fish has a smooth transition from its previous tank into yours. Using a quarantine tank will prevent illness and diseases from entering your main display tank.

Choose the acclimation method that works for you and make sure you have a system in place which will make acclimating any new fish in the future a routine.