When you receive a new saltwater animal you don’t want to just dump it
into its new home. You want to give it time to get used to any water
parameters that may be different from the water in the bag and the
water in the tank.
The basic idea of acclimation is that you slowly adjust the water in
the shipping bag of the animal until it matches the water chemistry of
your tank giving the new animal time to adapt to the new water
chemistry before release into its new home. Makes complete sense,
however, some ‘old aquarists tales’ have entrenched themselves in the
e literature and subconscious of aquarists and I think that these
ideas are at best a waste of time and at worse detrimental to the
health of the animal. Below, I hope to outline reasonable acclimation
procedures and present reasons why some of the ‘acclimation myths’
should be abandoned.
There are many ways to go about acclimating new animals to your
aquarium. Here is my rundown on the basics for a new animal that looks
healthy in a bag of relatively clear water.
Float the shipping bag in the new aquarium or sump to get the water in
the bag to match the temperature of the tank (if the new animal is a
fish or coral please use a quarantine system to avoid introducing
parasites to the show tank, but for cephs and other inverts this seems
not to be an issue). . This should take no more than 10 or 15 minutes.
Remove the bag from the tank and either decant the animal into a
bucket (making sure to put something under one side of the bucket to
tilt the bucket so the water is deep enough to keep the animal
comfortable) or open the bag and clip it to the side of the inside of
the bucket. If decanting you will be doing the acclimation in the
bucket, if clipping you will be doing the acclimation in the bag.
Either way, the goal is to make sure none of the bag water makes it
into your tank because it could be ‘infected’ with parasites, but more
probably its nasty from having an animal sit in it for 24+ hours.
Begin adding tank water to the bag or bucket. This can be accomplished
with a cup, or you can siphon water from the tank with an airline hose
equipped with a valve or tied in a couple of knots to control the
speed at which water is added. General rates of tank water addition
are 1/2 cup every 3-5 minutes, or if dripping, 1-3 drops per second.
If using a clipped bag you are looking to have extra water overflow
into the bucket over time. This process should take 30 minutes to an
hour, then move the animal to its new tank.
It should be glaringly obvious that there was no water testing
mentioned in the above procedure. This is because, really, once you
receive the animal you’ll have to do something with it regardless of
the availability of water testing and the above procedure is pretty
comprehensive. That doesn’t mean they can’t be useful. Mostly, we are
concerned with salinity, pH and temperature so testing those
parameters to determine when the tank water and the water the animal
is in match can reduce the acclimation time. You don’t want to adjust
any of these paramaters too quickly, but you also don’t want to
dawdle. It seems that there isn’t much to be done about most other
parameters, so testing doesn’t seem necessary except for the ones
mentioned above if possible.
The other parameter we care a lot about is ammonia, and it is
important to note that it is linked with pH. Ammonia can be lethal to
the animals, but its toxicity can be depressed by low pH. Over time in
a closed shipping bag the pH of the water lowers which is great
because the ammonia generated by the biological processes going on in
the bag is rendered less toxic than it otherwise might be. However,
once you open the bag and let fresh air in, the pH begins to rise and
the ammonia becomes more toxic. This is why I suggest temperature
acclimating while the bag is still sealed.
If the water is nasty when the shipment arrives, if you test and find
that ammonia is high, I would ignore most if not all of the
acclimation procedure and get the animal out of the toxic soup
immediately. Sure the other parameters may be off, but you have to get
the animal out of the toxic water. Its a risk, but I feel its one
worth talking because you know the bad water in the bag is killing the
All of the above can, of course, be modified based on your saltwater
common sense and experience. You have to trust you, and no recipe can
replace your developed saltwater thumb.
The biggest persistent myth I see is ‘the longer the acclimation the
better’ which has resulted in people going through the procedure for
2-8 hours (in at least once case – over night!). The idea that the
animals we are dealing with are fragile is true to some extent, but
they are also pretty robust within reason and can deal with reasonable
changes in environment. A super long acclimation just isn’t necessary
and can be detrimental – ammonia levels can rise, temperature in the
acclimating vessel can drop, and the animal can be stressed. Longer is
not necessarily better, so either test to make decisions or be
The other myth I see happening with some frequency is bubbling air
into the shipping bag. Sure it seems to make sense – the animal has
been in a bag for a long time and the oxygen must be depleted so give
it some. However, as we have seen above, this is the exact opposite of
what you want to do because the fresh air will increase the pH of the
water and will raise the toxicity of any ammonia that surely is in the
I hope this is helpful, and as always, please let me know if anything
is missing or if there are any questions.
Finally, here is a link to one of my favorite online vendors
Very interesting article. There are too many cases where people just dump water with fish right after coming back home and then blame LFS for killing their livestock. I do the dripping method, the acclimation kit cost less than $5 and I’ve never had problem with new introduced fish, be it either saltwater or FW.