Aiptasia (glass anemone)

Aiptasia

HarmfulDamages or kills individual corals if it's left alone.

A small brown or translucent anemone that arrives on live rock, frag plugs and coral bases. It is photosynthetic, so it needs nothing from you to thrive, and it stings — a colony next to one will lose tissue on that side. The problem is not the individual, it is the rate: it reproduces asexually and a tank goes from one to a hundred without a visible event in between.

Make sure that's what it is

Long, slender, translucent tentacles that taper to points, on a thin flexible column, retracting hard into the rock the moment water moves near it. The lookalike is majano, which has a short thick column and stubby tentacles with bulbous, often fluorescent-green tips. If the tentacles are club-ended rather than needle-ended, you are looking at majano and the treatment page you want is the other one.

What it looks like

No photos of Aiptasia (glass anemone) yet. If you have it in your tank, a clear shot here is what the next person will compare theirs against — it's the most useful thing you can add to this page.

Getting rid of it

In the order we'd try them. Every method cites where it comes from, and where the reason a treatment works isn't actually established, it says so.

Inject it where it sits

Chemical

Why it works

Aiptasia reproduces by pedal laceration: pieces of the pedal disc pinch off as the animal moves, and each of those lacerates develops tentacles and becomes a complete polyp on its own. That is the whole reason this pest is hard. A fragment left behind after you scrape one off is not debris, it is a propagule — so any method that detaches the animal instead of destroying it in place reliably produces more Aiptasia than you started with. Injection works because it kills the tissue before the animal can retract and tear.

What to do

Turn off return and powerheads so nothing drifts. Get the syringe tip to the oral disc — the mouth, not the tentacles — and inject until the anemone visibly swells and the tissue breaks down. Leave the flow off for the stated period so the agent stays put. Work on a few at a time rather than the whole tank in one session.

Careful: Everything that alarms the anemone before you dose it works against you: it retracts into the rock, tears, and reseeds. Do not scrape, cut or pull one first. Large infestations are not an injection problem — past a few dozen you are better off with a predator.

Source: Tentacle patterning during Exaiptasia diaphana pedal lacerate development (PeerJ, 2022)

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Aiptasia-XRed Sea

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No one has said this worked yet

Berghia stephanieae (nudibranch)

Biological control

Why it works

Berghia stephanieae is an obligate specialist: Aiptasia is the only thing it eats. It locates them chemically with its rhinophores, which means it reaches the ones causing the problem — the ones deep in rock crevices and inside overflow plumbing, where a syringe cannot go and where a hand-treated tank keeps reseeding from.

What to do

Add several rather than one, so they can find each other and breed. Turn the lights down for the first hours after adding them. Then wait: this is a slow method measured in weeks to months, and the population grows as it eats.

Careful: They starve once the Aiptasia is gone — that is the design, not a failure, but it means they are not a permanent garrison. Most wrasses, hawkfish and many other reef fish will eat them, so a tank with those is a poor candidate. Do not combine with a chemical pass that would also kill them.

Source: The Hero Called Berghia: Noble Nudibranchs for Biocontrol of Aiptasia sp. in the Reef Aquarium (Reefs.com)

Peppermint shrimp — read the species first

Biological control

Why it works

This one comes with a caveat that decides whether it works at all. "Peppermint shrimp" is a trade name covering several visually near-identical Lysmata species, and they do not behave the same: only Lysmata boggessi is consistently documented eating Aiptasia in both studies and aquarium observation. Lysmata wurdemanni — historically the name attached to the trade animal, and itself a complex of cryptic species — is not reliably associated with Aiptasia control. So "peppermint shrimp did not work for me" is very often a species problem rather than a method problem.

What to do

Buy on species, not on the common name, from a supplier that identifies what it is selling. Add them and give them time in a tank that is not over-fed, since a well-fed shrimp has no reason to work on a stinging anemone.

Careful: Even the right species is individual — some simply never take an interest. Some peppermint shrimp pick at LPS and zoanthids. This is a reasonable first try in a small tank and a poor plan for an established infestation.

Source: Peppermint shrimp — Lysmata species sold under the name (Wikipedia)

Keeping it out

It comes in on rock and on frag plugs, essentially always. Inspect and, where you can, remove the plug entirely rather than gluing it into the display — the underside of a plug is the single most common place one rides in unseen.

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