Aiptasia

Aiptasia are generally dark brown to translucent brown mini anemones.The brown color comes from zooxanthellae, a golden brown symbiotic alga. Aiptasia in our aquariums are usually less than 2 inches tall. In favorable conditions they may get as big as 4 inches tall. Aiptasia have long tapered tentacles.

Aiptasia are members of the phylum Cnidaria, and as characteristic of all Cnidaria have a stinging cell. These stinging cells, called cnidocyte, each contains a stinging mechanism, cnidae or nematocyst. The nematocysts of aiptasia have a toxin that is more potent that the majority of corals kept by the hobbyist. Corals coming into contact with aiptasia will recede and show signs of distress, leading to death. They can also reproduce quickly, over running an aquarium in a short period of time.

Aiptasia are introduced as hitch hikers in our aquarium. Often small specimens come in inadvertently on live rock or attached to the base of corals. Aiptasia are very common in shallow, nutrient rich water, but are also found in most tropical environments.

Aiptasia will reproduce quickly in some aquariums, while in others show little signs of an increase in population. The exact reason is unknown, but an environment high in nutrients and detritus seem to encourage faster growth. They generally reproduce by pedal laceration. When the aiptasia moves a small piece of the base tissue is left behind. Even a severely damaged piece can regenerate into an entire anemone. For this reason do not try to scrape the anemone off or try to crush it. Instead of killing it you will end up with many more.

Reproduction:

Spans an entire gamut, sexual and asexual. New individuals may form from a piece torn off during locomotion, your mechanical attempts at removing them, by longitudinal or transverse fission.

These sea anemones are of separate sexes. Fertilization and development occur outside the body cavity. The anemone larvae have a planktonic developmental phase before settling.
So how do I get rid of them?

Unfortunately there is no perfect answer. There are two basic approaches, natural predators and a chemical approach. I have had little success with the chemical approach but others report good success. The first step should be to create a low nutrient environment. While this will not eliminate them, it will be a deterrent for further growth.
The Chemical Approach

Various manufacturers have come out with different products. As of the writing of this FAQ’s, I know of none that works, or at least works any better than the old home brew.

The chemical approach involves taking a toxic liquid or paste and placing a large dose into the mouth of the aiptasia. The most popular one is to mix two parts water to one part calcium hydroxide (lime, kalkwasser) mix it and place it into a large bore syringe. Now this is highly caustic and some care should be given to the handling of this mixture. The large bore syringe can be obtained at any pet store or vet supply that handles vaccinations. Once you have it mixed and loaded, you simply place a large blob right on the aiptasia. The aiptasia rapidly takes the mix into its mouth. Within a few minutes the aiptasia begins to dissolve and can be easily removed by a small bore siphon. Other mixtures that can be used include hydrochloric acid, calcium chloride and boiling water. One more note of caution, large doses of some of these chemicals can rapidly change your pH.

My experience has been that while this seems to work well, there will always be traces of the anemone left behind that rapidly regenerate and you are right back where you started.

Another method has been to take the two part epoxies readily available and to seal them into the rock they live. This works well, as long as there is not an escape route for them to squeeze out on the other side.
Natural Predators

Human – Physical Removal:

Good luck here, these tissue-grade animals have a few tricks up their… tentacles. Try to rip, cut, pinch or siphon them out? They’re attached, and able to quickly withdraw, often into a tiny cranny. You remove most of the polyp… and the bit left regenerates into another (or a few) anemone! Nonetheless, with large infestations, a first line of offense is to physically extract as much of them as possible… I’d either do this with a siphon or remove the rock they’re attached to for scrubbing under a sink of running freshwater… you’ll only help the Aiptasia to asexually reproduce in your system by breaking it up and spreading it around there. Bad choice as it will only help them to reproduce more and faster in smaller sizes!!!

Berghia verrucicornis

Berghia verrucicornis along with most nudibranchs are diet specific. Then another article appeared in describing methods to culture it. Shortly thereafter starter cultures were exchanged and several Aquaculture facilities in the US begin producing them. As of this writing there are a limited number available and the specimens that can be found are generally too small be put in to a large system and expected to live. I am sure this will change in the near future.

The only drawback for these is that they will eat nothing else. Once there are no aiptasias left or so few the nudibranch has trouble finding them he will starve to death. This is also a problem with buying the very small specimens that are available, they might starve in a large tank before they are able to locate food. The solution would seem to be to have a small tank set up and culture aiptasia in them to feed the nudibranchs. An alternative would be keeping the Berghia in a 10 gallon aquarium and move infested rock into it. Once your problem has cleared up, you simply pass the Berghia on to a fellow hobbyist.

Elegance et al. Corals:

In the “who’s a better stinger” contest, the Meat/Elegance Coral (Catalaphyllia jardinei) rank near the top, higher even, than the Glass Anemones. If you could keep these mostly reef-system incompatible Caryophyllids alive and were willing to risk moving them about to sting your Aiptasia (but not other animals), your pest control problems would be over. FWIW, Hydnophora corals are also better stingers than Aiptasia as well.
Butterfly Fish

Chelmon rostratus and Chaetodon kleinii include these as part of their diet. I have had the best luck with the copper banded butterfly, C. rostratus. I have used these several times and they have never bothered any of the other inhabitants of my tank. I have heard reports of them picking at the small feather dusters in aquariums. The Raccoon butterfly is far less picky. While they eagerly devour the aiptasias, they also like to pick at other corals. They seem particularly fond of Trachyphyllia geoffroyii. Something to consider is fish are like people and have different tastes and at any time may change what they will eat. IMO dont even think about this buggers as they will wipe out your corals

Peppermint Shrimp

Both Rhynchocinetidae sp and Lysmata wurdemanni will eat aiptasias. Rhynchocinetidae sp. will also eat corals and is not suitable for a reef tank. There have also been reports of L. wurdemanni eating the polyps on small polyp sceleractinians. So I would think twice about adding this one.

Aiptasia-eating Shrimp, especially the Peppermint Shrimp, Lysmata wurdemanni (Image on the left), can be a great Aiptasia muncher. Be aware that there is some confusion in the trade re this species (from the Atlantic) and a few others including the native California coast Lysmata californica with darker, bolder dark striping… this latter Lysmata is no good as a designated Aiptasia muncher.

Hermit Crabs;

Perhaps the best (cheapest, most readily available, easiest to track and remove…) Aiptasia nemesis are a few Hermit Crabs. In particular the more common “Red Legged (“Hairy”) Hermit Crab, Dardanus megistos (Image) is an almost-all-the-time reef-safe animal that also eats pest algae. One or two to a tank is all it takes.