There are two different pest anemones that typically show up in a saltwater tank, both usually come in as hitchhikers on live rock. Both are typically only considered a pest if kept in a tank with corals or other sessile (immobile, can’t move) invertebrates as both will sting and invade these other organisms.
Aiptasia Anemone, is also known as the Glass Anemone.
The first is what is called an Aiptasia, or Glass Anemone. They are considered a pest due to the fact that they reproduce at astonishing rates, their strong stinging capabilities, and because of how difficult they are to eradicate. Many methods to get rid of them often result in causing them to spread even more. There are a number of marine invertebrates and fish that do eat them.
In this photo, you can see the Aiptasia stinging the smaller Mushroom coral, causing it to shrivel up and become irritated. If left to sting this Mushroom coral, it will likely kill it.
The number one most reliable Aiptasia control method is the Berghia Nudibranch, mainly because unlike the other animals its diet consists completely of Aiptasia. Berghia can be difficult because they often fall prey to other organisms while being introduced to the tank. Various fish such as the Copperband Butterflyfish, and the Emperor Angel will eat them, but both are questionable about how “reef-safe” they are. Peppermint shrimp will eat them occasionally, as will the Red legged hairy hermit crab.
There are a number of chemical means of attempting to control Aiptasia including Aiptasia-X by Red Sea, and Joe’s Juice. The problem with these is that when disturbed the Aiptasia actually emit spore-like offspring. Therefore, if not done right, it can make the problem worse. Another downside to using these chemicals, is that since they must be administered directly into the mouth of the Aiptasia, you can’t get the ones hidden away in the cracks and up behind all your rockwork. Essentially, with chemicals, you will only be able to get the ones in sight, and will never be able to fully rid your tank of them. I recommend, if possible, a natural method such as getting one of the animals listed above, as they will be able to get all the Aiptasia within the rockwork.
Majano Anemones are much more attractive than Aiptasia. In this photo, you can see the orange foot of the Anemone extending out, this extension will eventually break off and develop into an entirely new anemone.
The other pest anemone is known as the Majano anemone. It is much less of a pest due to the fact that it doesn’t reproduce at such a fast rate, and they are rather nice looking, ranging in a number of different colors from yellow to purple. Although they do look nice, and would blend into a reef tank or would add some color to a fish only display, they do still have the potential to sting other organisms. Some particular specimens can be quite beautiful and really only become a pest when they begin to propagate and invade other organisms.
There seems to be some skepticism into what methods work against these anemones. With Joe’s Juice receiving high praise.
In conclusion, both can be a pest, but only if allowed to get out of control or if they are bothering a sessile invertebrate. Ridding a tank of them can be a frustrating journey if you aren’t cautious and don’t do it correctly. There are many natural methods along with many chemical means of eliminating them. In an effort to do more research, and to test some of these methods, I have introduced both into my aquarium, as both were nowhere to be seen. I have already tested the Peppermint shrimp, and it worked wonderfully. Unfortunately, according to a number of sources, the peppermints shrimp’s willingness to eat the Aiptasia depends more on the individual, some loving them, some ignoring them. The next method to test will be the Berghia Nudibranchs, which I will be receiving later this week. So expect more on this subject in the future.