Acclimation is something that I had a flawed relationship with for a long time as a hobbyist, and I know I am not alone.  

It’s easy to get lazy with it when you lack the proper knowledge.  The reason is, there are plenty of instances in which you can basically completely abandon any precaution, and still end up with a successful introduction.  The problem comes in the next time, if conditions are not right to forgo a traditional acclimation but you don’t know how to properly assess the acclimation required in a given scenario.

There is really only one tool needed here to tell you everything you need to know!  Your salinity meter.

Temperature is also important, but very rarely do I see hobbyists  skip this step because it is so easy to do.  Simply float the bag in your tank, and allow the temperature in the bag to adjust to your tank temperature.

Once you open the bag, the first thing you want to do is test the salinity.  Not everyone knows this, but when purchasing livestock from stores and online suppliers you will see a tremendous range of salinities depending on where you are, and what tank the livestock came out of.  I have seen 1.014 all the way up to 1.029.  Even at our facility there is a big difference between the salinity of the fish rack and that of the Coral/Invert tanks (about 1.018-1.0265).

When the salinity of the water inside the bag very closely matches that of your aquarium, realistically little more than a temperature acclimation is necessary, its when these numbers are significantly different that a longer acclimation becomes vital.  Its also worth noting that going up in salinity during introduction is always harder on the livestock and therefore should be done over an increased period of time.  Fish racks will often have some medication or copper in them as well, so introducing the bag water to your aquarium can be a very bad idea.

SUMMARY:  Start by floating the back to equalize temperature.  Then test the salinity in the bag and your tank, and take not of the different.  Put the livestock in a separate container with the bag water to start, and begin adding water from your aquarium, a little bit at a time, taking note of increases in respiration rate or other signs of distress.  Between each addition of tank water, give the organism time to return to a calm state of behavior and respiration.  Once you think you have sufficiently acclimated the creature, check the salinity in the container.  If the salinity matches your aquarium water, you’re good to go.  If they do not, continue with the acclimation.