Enemy anemone...


Aiptasia and Jeremy Gay are sworn enemies. Here he reveals how you can declare war on and kill the brown menace.

If there’s one thing that drives me mad about reef tanks it’s Aiptasia, or rock anemones as they are commonly known.

I’ve dealt with months of red slime algae, clownfish after clownfish jumping out, high phosphates, low KH calcium and magnesium, all of which are fixable — but Aiptasia makes me want to hang up my refractometer for ever and admit defeat.

What are they?

Aiptasia are small brown anemones, typically less than 2.5cm/1” in diameter, with tentacles and on a stalk.

Unlike desirable anemones, these are hardy, reproduce quickly and can sting other corals.

A new reefkeeper may mistake them for polyps, yet these can move, quickly reach plague-like proportions — and are also a boring brown!

How do they get in?

They just creep in unnoticed on the rocks to which the corals are attached, or on live rock.

Aiptasia are expert hitchhikers which can live in sumps and pipework. You may even get one or two hanging onto Caulerpa or Chaetomorpha passed on between fellow reefers.

If moving corals or live rock from shop to tank you probably won’t see them, but, once in your tank, give it about 24 hours and you’ll be stuck with them.

They’ll travel out of water too, on wet live rock, so you’ll easily miss them when placing your rock as they will be shriveled and/or retreated into a tiny crevice.

Why spread?

As we improve at reefkeeping and make our tanks even more suitable for corals, we also make life more agreeable for Aiptasia.

These organisms thrive under good light, holding brown zooxanthellae within their tissues and providing them with food, but they also do well at catching and eating zooplankton aimed at feeding corals or any other foods, even dry fish foods.

They aren’t fussy as to light spectrum or intensity, or water flow, and, even worse, tolerate really unreef-like water conditions such as high temperatures, high salinity, yet low calcium magnesium and alkalinity. So if you’re struggling and doing most of the things wrong you’ll most likely end up with nuisance algae and nuisance Aiptasia!

The way we set up our tanks helps Aiptasia too.

Natural filtration means less emphasis on mechanical filtration and stronger pumps ensure that particulate matter is always in suspension. They spread when there’s lots of food about and when conditions are to their liking.

They can sting corals into submission and then stretch over their victim’s spot. I’ve even seen them on the base of larger corals.

Run a sump-based system with refugium, kill off all the Aiptasia in your main tank and more will emerge from pipework and the refugium below. In this vicious circle its almost impossible to totally eradicate them.

Prepare to take up battle stations!

Failing in any prevous efforts to kill them may even leave you with more Aiptasia, so wise up on some of these tactics….  

How can you kill them?

You cannot use copper in a reef system, as this will kill every coral, invert and critter in your tank.

Others measures include using Aiptasia treatments to kill them off outright or control them, or by using biological control like fish or inverts that are known to naturally predate anemones.

Use liquid remedies

These are the most widely available Aiptasia controllers. The idea with most is to inject a fluid either directly over or into the anemone at its stalk or disc.

Treatments tend to follow two main paths: by shock and awe using lemon juice or acid to literally blow up the anemone in its alkaline, salt water via sheer revulsion to the alien compound — or chemical warfare using calcium-based treatments which can sneak up to the anemone and smother it with a calcium overdose, or, if you’re lucky, injecting calcium straight into it, killing by calcium overload.

Both treatments will cause the anemone to immediately recoil into its hole and, as it expels water from its tissues, it will also expel as much of the alien fluid as it can in an attempt to survive.

I’ve tried most of the potions on the market and amazingly, almost all of my super-strong Aiptasia have survived, retreating into their holes for 48 hours before emerging victorious. They shouldn’t survive, but they do.

Failing that, use a multi-pronged attack. If you don’t kill one outright persevere over a week or so. All that anemone wants to do is come out and feed. Keep making life a living hell and you might just kill it.

Fish controllers

Introduce a fish which eats Aiptasia for a living. However many aquarium-suitable Aiptasia eaters don’t really eat them in the wild, like the “Aiptasia-eating” filefish — and also if they’re tough enough to eat an anemone despite a mild sting, they’re probably going to favour your corals first.

The best are the Copperband butterflyfish (Chelmon rostratus) and the Aiptasia eating filefish.

Copperbands aren’t brilliant in aquaria, acclimatising badly in all but the largest, most naturalistic reef tanks. Some demolish Aiptasia populations in days, others don’t touch them, but will eat all those desirable fan worms and critters you want for tank diversity.

Because of their size they aren’t suitable in anything smaller than about 300 l/66 gal either!

Next is the new kid on the block — the filefish. Most aren’t reef safe because they eat inverts, so reefkeepers take a risk and add one to their tank in the hope that they will eat Aiptasia and leave their corals alone.

Sometimes they are successful, but other times will target LPS and soft corals and then be a nightmare to remove. I’ve even had some that ate nothing, despite optimum water, and wasted away surrounded by Aiptasia.

Risky alternatives (Pic above by Jenny Huang, Creative Commons)

You can go for even more predatory butterflyfish, like the Klein’s. These aren’t even reef safe, so you would need to either remove all your corals — risking recontamination when you returned them — or introduce them to an SPS-only reef tank where the polyps are out of sight for most of the day.

Even then a known anemone eater may not target the anemones and the stubborn starvation game is not one you can play with delicate butterflies or filefish. They will just die.

Use inverts

The most famous Aiptasia-eating invert is the Peppermint shrimp, (Lysmata wurdemanni) but there’s also the similar L. californica or L. boggessi to consider.

True Peppermints have a red tail and red body stripes, but many other species have black or blue tails with silver stripes surrounding the red stripes. Sometimes it’s not easy to tell, but a well illustrated reference book will help identify the real thing — or find an experienced reefkeeper who knows.

Even then you may find that Peppermints are secretive, nocturnal, and may not even eat a single one, or leave the large ones. If you start to lose desirable polyps afterwards that may down to the pepps too, and getting them out from under a rock won’t be easy.

Reluctant to eat?

Worst of all is when your Aiptasia-eating filefish, Copperband or Peppermint shrimp refuses to eat a single one. This can happen all the time, as they might prefer fish foods or other foods.

Should you starve them into taking this anemone? No, as both fish species won’t survive anything less than very regular feeding, so you’ll just end up with corpses.

On the subject of eating I was amazed at what the anemones themselves can eat. I sat and watched once while a large Aiptasia caught the flailing polyps of my Pulse coral, cut them off and promptly ate them.

Try putty

If you’re feeling particularly nasty another way to kill these pests is with putty. Basically you get a small blob of reef putty and then block up the hole in the live rock into which the Aiptasia has retreated. Just check there isn’t another hole connected to it first.

A tiny issue with this is that live rock always open in structure, not sealed at every orifice.

Don’t let them in!

This tactic seems obvious, but for reasons I’ve explained, Aiptasia can hitchhike into your tank on nearly anything. As with all fish purchases, quarantine your live rock and coral for a couple of weeks first and look particularly closely for rock anemones. If you happen to find one it will be much easier to treat on a small lump of rock than on a full-blown reefscape.

Train your shrimp to do the job

I spoke to one retailer who had trained his Peppermint shrimp to eat Aiptasia exclusively, before selling them on to the public.

He therefore needed a ready source of his own, farmed Aiptasia and to breed them he would annoy them by stabbing and knocking them with sharp implements. They would then release their planulae which would grow on into adults.

So the moral of this story is if you manage to annoy your Aiptasia without actually killing them, they will simply produce more! Trained shrimp sounds like a good idea!

Try Berghia too

Berghia are nudibranchs (sea slugs) which are meant to prey exclusively on Aiptasia. They’re pretty tiny and when bought mail order may be as small as a grain of rice, so are fiddly and, once introduced, you may never see them again.

They should solve the problem, but when I added three to my 0.9m/3’ reef tank the Aiptasia reproduced more quickly than the tiny slugs could eat them. I guess I need more and of a larger size!

They won’t prey on anything else though, which is something of a bonus, and are cultured in captivity.

Top pests: Aiptasia versus majano

Majano anemones are pests too. I regard these as much more pretty than Aiptasia but they become invasive across the rock structure, spreading and overgrowing everything.

Physically remove them with tweezers in their early stages of growth — although I don’t put their level of terror quite as high as Aiptasia.

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