Impressions of Methods to Eliminate Pest Anemones

By Steven Pro

There are various methods that hobbyists have tried in an effort to rid themselves and their display of the pest anemones Aiptasia and Anemonia majano. Some have attempted various methods of chemical warfare while others have employed biological means to eradicate these pests and still others have attempted physical removal. These techniques each have their various pros and cons; all of these work sometimes, but they also fail sometimes, too. In that regard, I have found a few ways that I prefer over others. Usually, the reason why I prefer one method over another falls under one of several categories; the first reason being that it seems to work more often. Another good reason to pick a method is because it is easier to apply. And lastly, some of these techniques are less risky than others.

Wanted... not "dead or alive," just dead! Aiptasia sp. (top) and Anemonia cf. majano (bottom)

The Bad Guys

Aiptasia

Aiptasia, commonly referred to as "Glass" or "Rock Anemones," are a frequently encountered pest anemone. They are typically a translucent cream to brown color with tentacles that come to a point. Often you will hear people describe them as having a "flower-like" appearance. Even though that is a pretty good description, they are not a delicate flower. They are much more similar to an invasive weed. Think of them as the tough little Dandelion of the aquarium hobby. They are unattractive, reproduce easily, have powerful stinging nematocysts which can harm or outright kill the corals or clams in the tank, and they can be challenging to eradicate. Aiptasia are native to the Caribbean, but are often introduced through hitch-hiking on corals and rock that has been kept in systems where Aiptasia have been introduced.

Anemonia majano

These are the prettier of the two common pest anemones. I have seen specimens in green, red, and even a striking yellow. They are somewhat less of a nuisance than Aiptasia, partially because they are somewhat attractive, but primarily because they are not nearly as prolific. They can be easily distinguished from Aiptasia because they have bulbous tips on the ends of their tentacles. Unfortunately, like Aiptasia, they have a potent sting and can become a danger to the other sessile invertebrates in the aquarium. Anemonia are Indo-Pacific in origin.

Biological Means of Control

Berghia

Berghia nudibranches attacking an Aiptasia anemone. These beautiful creatures are easily cultured and are an effective control for aiptasia, but since they easily fall victim to predation, they work best when infested live rock can be removed from the display for "cleaning." Photo by Anthony Calfo

These little nudibranches are natural predators of the pest anemone Aiptasia. In fact, that is all they ever eat, so they are a perfect choice for ridding your tank of Aiptasia. But, they do have some problems. Mainly, they are hard to find. Few local fish stores carry them. I have mostly been able to find them at specialty online vendors or in trade from other hobbyists. Secondly, they are expensive. The old rule of supply versus demand keeps their price dear. Third, many people sell them when they are too small and underdeveloped. This causes unnecessary losses in transit. And lastly, you can’t just buy a couple, toss them into your display, and expect them to find and eat all your Aiptasia. It just doesn’t work that way. Most of the time, they just disappear without doing anything if merely tossed into a reef tank. They likely fall prey to fish or other invertebrates when used in this manner. The best way to utilize these nudibranches is to keep them in a separate tank where they are protected and transfer pieces of infested rock from the display into their little world where they can clean it. Once a piece of live rock is free of Aiptasia, it can be replaced in the main display and a new piece of rock can be transferred for cleaning. This process is tedious, but it is hands down the most effective method. As an added benefit, these nudibranches breed so readily that you will soon be rewarded with eggs and offspring by keeping them in isolation. Berghia are, in fact, quite prolific. Even at the age of 7-8 weeks old, young adults are capable of producing an egg ribbon every other day when well fed. The potential of turning a couple of adults into hundreds to help you in your battle against Aiptasia in just a few months is quite possible! You may even be able to rid your tank of this pest anemone and make a few bucks by selling your extra nudibranches!

Catalaphyllia jardinei, the Elegance Coral, is capable of damaging pest anemones with its powerful sting.

Elegance Corals

This method was originally reported by Julian Sprung in his Reef Notes column in Freshwater And Marine Aquarium (FAMA) magazine. It was republished and repackaged in his little Reef Notes book Volume 4. The source of the suggestion is attributed to John Brandt from Chicago. You may have heard that name, since he is actively involved in the Marine Aquarium Society of North America, MASNA, the people that sanction the annual convention known as MACNA, the Marine Aquarium Conference of North America. The idea is that the strong stinging nematocysts of the Elegance coral, Catalaphyllia jardinei, could be used to kill the Aiptasia. While this may possibly work, Elegance corals routinely suffer upon import nowadays. It is frankly unusual to hear of someone being able to keep one long-term lately. As such, if you were to find a healthy one, I would not recommend risking it in a battle royal with Aiptasia.

In all fairness to Mr. Sprung, he originally suggested this method when Elegance corals were considered a hardy coral. Back in the day, they were a good beginner’s coral. Now, most suffer and die from unexplained causes. There is one ongoing study by Eric Borneman that is looking into why they no longer seem to thrive in captivity, but regardless of the outcome of this experiment, I doubt most people would be willing to jeopardize their newest, pretty acquisition on an ugly pest anemone when other means are readily available, less precarious, and certainly not as expensive.

Chelmon rostratus, the Copperbanded Butterfly, is widely used to control Aiptasia sp.

The Pomacanthus imperator, the Emperor Angelfish, will often prey on Anemonia sp. It can be risky to house this fish with desirable anemones and corals.

Fish

There are numerous fish that are sometimes mentioned to help control pest anemone problems. The Copperbanded Butterflyfish, Chelmon rostrata, is the mostly commonly recommended to prey upon Aiptasia. Some aquarists also advocate the Raccoon Butterflyfish, Chaetodon lunula, for controlling Aiptasia the Emperor Angelfish, Pomacanthus imperator, is sometimes utilized against Anemonia majano. None of them is guaranteed to eat the target organism. But even if they do eat them, more often than not, they also nip at some specimens that the hobbyist doesn’t want them to attack. Copperbanded Butterflyfish are generally safer than the other two, but they are known to also prey upon feather dusters/tube worms and might sample the occasional large polyp stony coral, SPS, soft coral, or clam. The Raccoon Butterflyfish is not considered to be ‘reef-safe’ and neither is the Emperor Angelfish. The Raccoon will consume just about anything that one would house in a reef display while the Emperor will be a little more discerning. LPS corals, some soft corals, anemones, and clams are more at risk in comparison to SPS or the more noxious soft corals. If you attempt to use any such fish predator, be sure to train it properly by feeding it pest anemones while in quarantine before introducing it into the infested display. This way, you will know before hand if you will have an assistant in your battle against the anemones or merely a beautiful addition to your display which may also nibble on desirable organisms while ignoring the targeted pests.

Hermit Crabs

The Red- Legged Hairy Hermit Crab, Dardanus megistos, has also been recommended as an Aiptasia predator. While they do seem to eat Aiptasia I am generally reluctant to place hermit crabs in my reef display. All hermit crabs, and crabs in general, are opportunistic omnivores. That means they will basically try to eat just about anything they happen upon that is edible. This can run the gamut from desirable algae, mysid shrimp, amphipods, worms, and even some corals. It is my opinion that few crabs are completely safe, practical, or recommended for most reef aquariums.

The Lysmata wurdemanni, the true Caribbean Peppermint Shrimp, will often eat Aiptasia sp., but as seen in this picture, they will often also kill and eat desirable tankmates. Beware of very close look-alikes, especially the destructive Camel Shrimp.

Peppermint Shrimp

Peppermint shrimp, Lysmata wurdemanni, have been recommended to clean up Aiptasia in display tanks. Basically, they work sometimes. I have had tanks where I introduced a few and within weeks all the Aiptasia were gone. In other instances, they don’t seem to eat any Aiptasia , and instead concentrate on stealing food from fish and corals. I have even witnessed them attacking and eating small feather dusters and Astraea snails, so I would say these are at best hit or miss. The one thing to watch out for if you select this method is to be sure that you get the true Peppermint shrimp. You are looking for Lysmata wurdemanni. These are collected out of the tropical West Atlantic Ocean/Caribbean. There are several other shrimp that are also imported and are occasionally mistaken for Peppermint shrimp. The most commonly available is Rhynchocinetes durbanensis, also called the Camel Shrimp or Dancing Shrimp because of the distinctive hump on their back. These are easy enough to distinguish, though. Additionally, there are two other species of Lysmata shrimp that are occasionally available and much easier to confuse with the true Peppermint shrimp. Lysmata rathbunae and Lysmata californica are similar and alleged to be not as likely to consume Aiptasia. Both of these also hail from cooler water, so there is some concern for their long-term viability in typical warm water reef displays.

Kalkwasser and Joe's Juice are effective chemical means used to control pest anemones.

Chemical Means of Control

Joe’s Juice

This is a newer product to enter the market. You are supposed to squirt, or coat, the pest anemones you wish to kill with its chalky white liquid. I have found it works pretty well. It takes multiple applications as with the first use it seems to merely knock down the anemones. In my experience, they come back albeit smaller after the first exposure. Hitting them numerous times can completely destroy the pest. The biggest drawback to this method is how tedious it can be if you have a number of pest anemones to destroy. It is also comparably expensive to other chemical means such as kalkwasser. You only get a small 20 ml container of the chemical along with an application syringe upon purchase for around $7.00 from various online vendors. For comparison, you can almost buy a one pound tub of kalkwasser powder for about the same money.

Kalkwasser/Calcium Hydroxide

Killing pest anemones by either injecting them with a kalkwasser mixture, or slathering them with a paste-like slurry of calcium hydroxide is a tried and true method. It is my usual preference, but it can be quite tedious if you need to eradicate many anemones. It generally must be repeated multiple times to affect a complete cure, and you must be careful when applying it for fear of collateral damage to sensitive cohabitants that are nearby. On the plus side, many hobbyists already have calcium hydroxide on hand for use to maintain/supplement calcium and alkalinity. Also, if you are already dosing limewater any excess kalkwasser is merely going to contribute to your calcium concentration versus some other targeted poison which is left to drift with the currents throughout your tank.

Other Chemicals

There is a whole host of other aqueous solutions that people have used to attempt to kill pest anemones with by means of injection: boiling water, hypersaline water, lemon juice, muriatic acid, pepper-based liquids, and vinegar are just a few that come to mind. The first hurdle with any of these injectables is actually trying to stick one of these anemones with a needle. The anemones won’t stand still while you attempt to jab them. They usually retract down deep into a hole whenever you even get close to them making injections a challenging activity, to say the least. Secondly, even if you manage to get lucky and properly inject and kill one, how many more do you have to eliminate? You should be able to see that this is a rather daunting task if the tank is overrun with pests. Lastly, with the exception of boiling water and hypersaline water, I am reluctant to add these other chemicals to my tank. Kalkwasser is simply calcium hydroxide and is a preferred method of delivering and maintaining calcium and alkalinity. Hence, small excesses of this compound which are carried away in the currents of your aquarium are not likely to have a negative impact. Although, if you add an extreme amount of kalkwasser, you can spike the tank’s pH to dangerous levels and harm the occupants.

Physical Means of Control

Do your best Tony Soprano impersonation and say, “Fagetta baat it.” Siphoning, scrubbing, cutting, and most other attempts to physically remove pest anemones are only going to end up propagating them. Any tiny portion of the anemone that is left behind or cut from the parent and blown away in the currents can grow to become another new pest.

I have even seen and read of people trying to smother pest anemones with underwater epoxy. The few instances I have actually witnessed this attempted were not successful. Even if this worked, you would be left with a bunch of unsightly patches of underwater epoxy all over your display. Who wants that?

Conclusions

I would be remiss if I did not mention something else concerning these pest anemones. They are like other anemones, and really cnidarians in general; they cannot survive on light and the products of photosynthesis alone. They must be fed to live, grow, and multiply. In many instances, a proliferation of pest anemones should also be a wake up call to the aquarist to reexamine their husbandry techniques. Over feeding or inappropriate feeding, dosing the tank with suspect additives and invertebrate foods, and poor nutrient export processes are all likely contributing factors in many instances where these pests get out of control. A thorough, thoughtful retrospective on the care you provide may yield some additional measures that you can institute or perhaps some refinement of your current practices to help you in this battle by starving the creatures into submission.

So, what should you use? That is hard to say. Much of making this decision has to do with your particular set of circumstances and what kind of work you want to put into it. I can tell you what I would use. Berghia nudibranches are far and away one of the best choices because they are both 100% safe and effective when used properly. They are guaranteed to eat Aiptasia and won’t bother anything else. You can even make a few bucks on them because they breed so readily, have a high demand, and command a good price. Copperbanded Butterflyfish and Peppermint Shrimp are not bad choices, either. Both work sometimes. You just have to observe your animals carefully and be prepared to remove these Aiptasia predators if they start preying upon other desirable organisms. Lastly, Joe’s Juice and kalkwasser are both moderately effective, although more work than the various biological methods. Plus, kalkwasser is readily available and much cheaper than Joe’s Juice, hence it gets my recommendation for a chemical means of eradication.