Aiptasia: how to get rid of it

Quick reference

What are Aiptasia?

Aiptasia is a genus of more than a dozen small anemones, known to reefers as glass or rock anemones: usually under an inch or two tall, transparent to brownish, with long, pointed tentacles.^{[1, 2]} The brown comes from zooxanthellae, the same symbiotic algae corals carry.^[1] It arrives as a hitchhiker on live rock and coral, and TFH notes it persists in dim spots, unlit sumps and overflows, which is why it so often seems to come from nowhere.^{[1, 4]}

How to get rid of Aiptasia

Act at the first one: TFH's advice is to take action immediately, because waiting lets them spread.^[1] Whatever method you use, the rule is the same: kill it in place or take it out whole, because torn tissue regrows.^{[1, 4, 2]}

Spot treatment for a few anemones. Injecting kalkwasser (calcium hydroxide) into the mouth with a syringe is the method LiveAquaria calls the safest chemical option; lemon juice, hydrogen peroxide, commercial kalk products and hot RO water are also used.^{[3, 1]} The catch is aim: the anemone retracts into the rock when touched, small ones are hard to hit, and an incomplete kill can regrow as several new anemones.^{[1, 4]} Bulk Reef Supply's method is Frank's F-Aiptasia, a topical product that covers the anemone and forms a hard crust that traps fragments; turn the pumps off first, treat only a few at a time, and keep it off coral polyps, which it can also kill.^[2] For one in a hole, BRS and TFH suggest sealing it in with a dab of epoxy or coral glue, topped with F-Aiptasia.^{[2, 1]} Electrical zappers work on anemones they can reach but are slow on a big infestation.^[1]

Take the rock out. Reef Builders' Andrea Ehlers prefers removing the anemone with the rock: cut around it with coral cutters and siphon it out, or scrape it off the glass with a razor blade, so nothing breaks loose in the tank.^[4] Treating rock in a separate container is safer than treating in the display, and boiling kills every Aiptasia on it, along with everything else.^{[4, 1]}

For an infestation, use predators (below), and keep spot-treating new ones, because Bulk Reef Supply says new anemones will inevitably pop up.^[2]

What it lives on

It carries its own zooxanthellae, the symbiotic algae that make it brown.^[1] LiveAquaria warns that it won't leave on its own and that feeding extra nutrients won't help matters.^[3]

Why it's a problem

Its sting is strong for its size: TFH says it can damage or kill soft and stony corals and sting the mantles of Tridacna clams, while most corals can't sting back hard enough to stop it spreading.^[1] Reef Builders adds that it stings some fish, such as seahorses.^[4] Bulk Reef Supply describes it spreading like wildfire.^[2]

What eats it

Berghia nudibranchs eat only Aiptasia, and Bulk Reef Supply calls them the most effective livestock option; Ehlers' Berghia cleared all the Aiptasia in a 20 gallon nano over a few months, but they starve once the food runs out.^{[2, 4, 5]}

Peppermint shrimp (Lysmata wurdemanni or L. boggessi) eat Aiptasia, usually the smaller ones, but not every shrimp does, and they may nip coral polyps; in feeding trials with a related shrimp, hungry shrimp ate far more than fed ones.^{[2, 1, 6]} TFH warns that the camel shrimp, Rhynchocinetes durbanensis, is sometimes sold as a peppermint and is not reef safe.^[1]

The bristletail or matted filefish stays about 3.5 in and suits tanks of 30 gallons or more, captive-bred fish being easier.^{[2, 4]} The copperband butterflyfish is TFH's most reasonable fish option, but it's a finicky eater best left to experienced keepers, and some nip feather dusters, clams or small-polyp stony corals or ignore Aiptasia altogether.^{[1, 2, 3]}

Prevention

Inspect every rock and coral before it goes in, and pick off any small anemone you find; it arrives as a hitchhiker on both.^{[1, 4]}

How it spreads

It reproduces sexually and asexually. As it creeps across a surface it leaves tiny bits of tissue behind that grow into new anemones, so one parent can produce many; any scrap left after cutting or scraping can do the same.^{[1, 4]}

Troubleshooting

Common mistakes

• •Pulling or scraping it off in the display.^{[1, 4]}
• •Waiting until there are dozens.^[1]
• •Running pumps while applying F-Aiptasia.^[2]
• •Buying a camel shrimp sold as a peppermint.^[1]
• •Expecting peppermint shrimp to clear large Aiptasia.^{[1, 6]}

Aiptasia FAQ

What kills Aiptasia instantly?

Injecting kalkwasser or a commercial product into the mouth, or covering it with F-Aiptasia, kills a single anemone, if you hit it before it retracts.^{[3, 1, 2]}

Do peppermint shrimp eat Aiptasia?

Often, mostly small ones, but not every shrimp does.^{[1, 2]} Hungry shrimp eat far more than well-fed ones.^[6]

Are Berghia nudibranchs worth it?

Bulk Reef Supply calls them the most effective livestock option; they eat only Aiptasia and starve once it's gone.^{[2, 5]}

Is Aiptasia harmful?

Yes: it stings corals, clam mantles and some fish, and spreads fast.^{[1, 4]}

Can I just scrape Aiptasia off?

Not in the tank: leftover tissue regrows into more anemones. Remove the rock or kill it in place.^{[1, 4]}

Does lemon juice kill Aiptasia?

It's one of the injected treatments TFH and LiveAquaria list, alongside kalkwasser and hydrogen peroxide; delivery is the hard part.^{[1, 3]}