Majano Anemone: Reef Pest Identification, Control & Removal

Majano anemones sting and overgrow corals, spreading fast by pedal laceration. Learn to identify, control, and safely remove this reef pest.

Overview & Identification

The majano anemone (Anemonia majano) is a small pest anemone that turns up in reef aquariums, where it stings and crowds out prized corals. The genus Anemonia (Risso, 1826) belongs to the sea anemone order Actiniaria within phylum Cnidaria, and like all sea anemones its body is built from a basal pedal disc, a cylindrical column, and an oral disc ringed with tentacles.

Identification matters because majanos are often confused with Aiptasia, yet the two respond to very different controls. Like many anemones, majanos host photosynthetic single-celled algae (zooxanthellae); the anemone benefits from the products of the algae's photosynthesis, while the algae's identity largely determines the animal's color. This symbiosis lets majanos thrive under bright reef lighting.

Where They Come From

Majanos almost always hitchhike into a tank on live rock, coral frags, or their plugs. Because sea anemones can reproduce asexually, a single unnoticed individual is enough to seed a population: a ring of material breaks off from the pedal disc at the base of the column, fragments, and each piece regenerates into a new clonal individual. This pedal laceration is why majanos spread without any partner.

Harmful or Beneficial?

Majanos are harmful in a reef display. Sea anemones carry cnidocytes containing stinging nematocysts, capsule-like organelles that suddenly evert a harpoon-like structure to deliver venom. Majanos use these stinging cells to damage neighboring corals and compete for space and light, so an unchecked patch will steadily overgrow a reef.

Control & Removal

Physical and chemical removal is the front line. Where a majano sits on a removable piece, take the rock out and scrape the anemone off, taking care to remove every portion because it can grow back from even a tiny part of the foot. For attached specimens, eradication products such as F Aiptasia are formulated to target pest anemones including Aiptasia and majanos.

1. Remove the affected rock or frag from the tank when possible and scrape off the entire anemone, foot included.
2. For fixed rock, inject or apply a pest-anemone eradication product (e.g. F Aiptasia) directly onto the anemone.
3. Add a natural predator: the captive-bred Bristletail filefish (Acreichthys tomentosus) is raised on pest anemones and is generally considered reef safe.
4. Note the Berghia caveat: Berghia nudibranchs are the classic Aiptasia answer but do not reliably target majanos, so do not rely on them.

Prevention

Stop majanos before they arrive. Quarantine and inspect every new piece of live rock, coral, and frag plug, and dip or cull suspect hitchhikers before they enter the display. Because asexual fragmentation can rebuild a colony from a scrap, deal with the very first individual you spot rather than waiting.

Common Mistakes

The biggest mistake is confusing majanos with Aiptasia and reaching for the wrong tool, such as Berghia nudibranchs that ignore majanos. The second is impatient manual removal that leaves foot fragments behind, seeding new colonies. Treat majanos deliberately, remove every scrap of tissue, and pair physical removal with a proven predator or eradication product.