Haplochromis (CC BY-SA 3.0)
Majano anemones
Anemonia majano (also written Anemonia manjano in older hobby literature)
Pretty, fast-spreading pest anemones with a potent sting that colonize rockwork and overgrow corals, and aiptasia remedies mostly fail on them.
Identification
Small anemones up to about 3 cm across, sitting low on the rock on a short, thick column. Greenish-brown to tan, often with brighter green, pink or cream coloring that can look attractive under blue light. Tentacles are short, crowded and thick, ending in rounded, clubbed or bubble-like tips. Common on live rock and around coral bases, frequently in clusters.
Often confused with
Aiptasia — aiptasia stand taller on a thin stalk with long tentacles tapering to sharp points; majano tentacles stay stubby and blunt. Also confused with ball anemones (Pseudocorynactis), which carry one distinct ball on each tentacle tip, hide in shade and come out at night, and with small bubble-tip anemones, which grow much larger and do not carpet rock in clones.
What it targets
No fixed host. They plant on rock, plugs and coral skeletons and sting and shade out nearby corals, including SPS, LPS and zoanthids, as colonies expand.
How it spreads
Hitchhikes on live rock and coral purchases, sometimes deliberately kept at first because it looks like a tiny bubble-tip. Spreads by splitting and pedal laceration and can reach plague proportions in nutrient-rich tanks.
Control (safest first)
Manual plucking: majanos are more leathery than aiptasia and often peel cleanly off smooth rock with tweezers when you can get under the foot; siphon the spot afterward. Any flesh left behind can regenerate, so scrape and rinse removed rock outside the tank. A few days of darkness can coax buried polyps to climb toward light and loosen their grip, per WetWebMedia advice. Kalkwasser (calcium hydroxide) paste: mix to a toothpaste consistency, turn pumps off and cover the whole polyp. Widely reported to work on majanos; treat only a handful per day to avoid pH spikes, keep paste off neighboring corals, and wear eye protection — one forum report describes a syringe of fresh kalk paste spurting and causing serious eye damage. Commercial aiptasia products and injection of hot water or lemon juice: results are mixed and usually weaker than a full kalk-paste covering; a polyp that retracts into a hole before treatment usually survives. Majano Wand: purpose-built electrolysis wand named for this pest; a Reefs.com reviewer found it easier and more effective than kalk paste over several weeks of repeat passes, with pests recovering more slowly, though reach and rock position limit it. Predators: only large angelfish (emperor, majestic, blueface) and some non-reef-safe butterflyfish reliably eat majanos, per WetWebMedia — impractical and coral-risky for most reef tanks. Berghia nudibranchs and peppermint shrimp do NOT eat majanos; buying them for a majano problem wastes money.
Natural predators
Field notes
A WetWebMedia keeper described an olive-green anemone with pink tentacle tips, about an inch across, that arrived as a cute hitchhiker on live rock and exploded across a 75-gallon reef; the crew identified it as Anemonia majano and warned that the usual aiptasia predators show no interest in it, while noting leathery polyps can be plucked cleanly when the base is reachable. A Reefs.com reviewer who had been managing pest anemones with kalk paste switched to the Majano Wand and reported making a real dent over several weeks of passes every few days, with treated spots recovering more slowly than after kalk — while still calling the wand one tool among several rather than a magic bullet. Keepers disagree on how aggressive to be early: some treat three dime-sized polyps as an emergency because a previous tank was overrun, while others have kept a few majanos for long periods without spread — the common thread in the bad outcomes is waiting until clusters are established deep in the rockwork.