Rules of thumb:
1) Make sure they are alive
We have done extensive experiments with packaging and posting Berghia, nevertheless, there is a small chance they can arrive dead. Watch them for a good minute, they are slow moving animals. If they are attached to the sides of the container, they are alive. They will appear smaller after shipping, especially when balled up. They will grow after they stretch out and have a chance to eat.
Start acclimating them as soon as possible as below, or at the very least, unscrew the lid of the container. They are in a confined space and do better at cooler temperatures than your tank is likely at. As tempting as it may be, please do not put the container in your sump.
Based on experience, it can take them a good while to get over the shocks of shipping. Even if they look dead, there is a good chance they will be fine in the end.
2) Acclimation:
The water of every marine tank will be slightly different, and as Berghia are sensitive invertebrates, you will need to get them used to your tank’s water slowly. This process should take 45-60 minutes. Unscrew the lid of the container, pour about half the water out and gradually add small amounts of water. This should take about 20 minutes. Once the container is full again, repeat the procedure, making sure that the temperature of the container stays the same as the temperature in the tank.
In case the Berghia are crawling on the lid, shake the container gently, so they let go and sink to the bottom.
3) Releasing the Berghia
Ideally, wait until the lights go out above the tank. Find a quiet corner in the aquarium with Aiptasia around and place the container between two rocks and let the Berghia crawl out on their own. I have found this to be the best way of releasing them. You may have to put a small piece of rock inside the container to weigh it down.
4) Catching Berghia
Should you need to catch your Berghia at any time, please use the included cut off pipette. Shoot some water at their feet and once they have let go of the surface, you can suck them up.
5) Filter floss and rollers
These nudis tend to find their way from the sump to the tank and back. The big obstacles they can face are filter floss and rollers, where they can get trapped. This is not a problem with every tank, but it can be a problem. As a solution, consider removing them until the nudis have done their job.
Please see the other side on what you can expect.
What you can expect
The short version is, that once you put your Berghia in, you will not see them for 10-12 weeks, by which time, if everything went well, all your Aiptasia will be gone.
The longer version is, that once you release them in your fish tank, Berghia will go and hide. They are nocturnal hunters and they like to hunt in groups. They will start consuming Aiptasia right away. You can actually tell how hungry they are by their color. The whiter they are, the hungrier they are. The more they eat the more brownish they become.
The Berghia you have received can only do so much damage. They are small animals and eat in proportion to their size. Aiptasia are very prolific, so there is a chance the Berghia can only slow their spread.
The power of Berghia is in numbers. They will lay so called eggs swirls in your tank, potentially giving life to hundreds of little Berghia. Once these have had a chance to grow up, there is no amount of Aiptasia they will not devour.
Once the Aiptasia is gone, you will see white, and hence hungry, Berghia roam the tank even during the day looking for food. This is when you can catch some and give them to fellow aquarists.
Unlike other natural Aiptasia control methods, Berghia chew down to the rock, eating every bit of the Aiptasia. There is a slight chance the Aiptasia will come back with time, simply because the last hungry Berghia could not find the last bit of Aiptasia.
Good luck.
PS:
Egg swirls
If you have received an egg swirl, after acclimating it along with the Berghia, shoot it into a crevice in a rock near a small Aiptasia with the included pipette.
PPS:
Added protection
Berghia are the safest when they have eaten, as they take on the stinging defences of Aiptasia. If you can, place your nudis into a larger tub of tank water, a one-liter one should be fine, and feed them before you introduce them to your main tank. You will notice they will turn a dark brownish color. Once they are dark, they are ready to be introduced. This should be a quick process, definitely less than two hours.
People have had plenty of success without this last step, but if you want to increase your chances, especially if you have wrasses in the tank, this step should help.