Majano anemones: how to get rid of them

Quick reference

What are majano anemones?

Reefs.com describes majanos as small, light brown anemones with short stalks that often, but not always, have bubble tips.^[2] CORAL's Marc Levenson first mistook them for tiny bubble-tip anemones in a store, bought four for $20, and a few weeks later had about 50 in his 29 gallon tank.^[1] Unlike Aiptasia, which can hide anywhere in the rock, majanos need light, so they sit in plain view and climb glass, corals, powerheads, cords and even cleaning magnets.^[1]

How to get rid of majano anemones

Out of the tank, piece by piece. Levenson's chemical-free method: take out one piece of rock at a time, scrape each anemone off, chip away rock with bone cutters where needed to get all the tissue, check under blue light for stragglers (often on the underside), wipe tools on a sponge, and return each clean piece before starting the next. Wear eye protection: they can squirt. His tank didn't cycle and the coralline wasn't affected.^[1] Work promptly, because majanos move and spread while you're at it.^[1]

In the tank, Reefs.com says they can be pulled off with tweezers or cut away with a scalpel or razor blade, or injected with hot water, vinegar or a commercial product.^[2] WetWebMedia's Mike V. prefers injecting kalkwasser paste, and Bob Fenner advises against boiling rock, which he says can release toxins.^[3]

What it lives on

They need light and live on their symbiotic algae.^[1] Nutrients drive them: WetWebMedia's Scott T. says that in an understocked, properly fed tank they won't multiply much at all.^[3]

Why it's a problem

Bob Fenner says a single majano beside other cnidarians is not likely a problem, unless there's a bunch of them crowding them.^[3] Levenson calls them the reef aquarium's equivalent of Tribbles: they spread rapidly and cover rock that could hold corals.^[1]

What eats it

No predator is reliable. WetWebMedia lists peppermint shrimp, butterflyfishes and filefishes among reported pest-anemone eaters, and Scott T. suggests a juvenile emperor angel might help, but few fish that eat anemones are reef safe.^[3] We found no good evidence that Berghia nudibranchs, which eat only Aiptasia, eat majanos.^[4]

Prevention

Examine and clean every rock before it goes in.^[2]

How it spreads

They tear themselves in half to multiply, and any tissue missed during removal may grow into a new anemone.^{[1, 3]}

Troubleshooting

Common mistakes

• •Buying them as tiny bubble-tip anemones.^[1]
• •Scraping them off in the display.^{[1, 3]}
• •Boiling the rock.^[3]
• •Adding Berghia for majanos.^[4]

Majano anemone FAQ

How do I tell majanos from Aiptasia?

Majanos sit in the light, often with bubble-tipped tentacles, and climb glass and equipment; Aiptasia can hide anywhere in the rock, even in dark spots.^{[1, 2]}

Do Berghia eat majanos?

We found no good evidence they do; Berghia feed only on Aiptasia.^[4]

Are majanos harmful?

One or two rarely are, Bob Fenner says; a carpet crowds out corals.^{[3, 1]}

What kills majano anemones?

Injecting kalkwasser paste, hot water or vinegar kills ones you can reach; scraping rock out of the tank removes the rest.^{[3, 2, 1]}

Why do I have so many majanos?

They split to multiply, and nutrients fuel it.^{[1, 3]}