Bali Fire Anemone

Branching Tree Anemone, Stinging Anemone, Hell's Fire Anemone

Bali Fire Anemone, Megalactis hemprichi, Branching Tree Anemone, Stinging AnemoneMegalactis hemprichiPhoto © Animal-World: Courtesy Greg Rothschild

Divers and aquarists beware of the dangers of the Bali Fire Anemone! It has an extremely powerful sting that is very painful!

The Bali Fire Anemone Megalactis hemprichii (syn: Megalactis hemprichi) looks more like a coral than an anemone. But beware, their sting is much more powerful! Aquarists and divers alike, be warned, wear gloves when handling this genus and when diving do not have them come in contact with any bare skin. Although all anemones have stinging cells or nematocyst found in their tentacles, these anemones have a dangerous sting that is extremely powerful and is very painful. They have been known to sting divers quite badly.

This anemone belongs to the Megalactis genus, and is one of the 'stinging sea anemones' in the Actinodendronidae family. This family consists of three genera; Actinodendron, Actinostephanus, and Megalactis, all of which are found only in the tropical waters of the Indo-Pacific. They are so named 'stinging sea anemones' because of their capacity to sting humans badly. The Bali Fire Anemone is similar in this regard to the Hell's Fire Anemone Actinodendron plumosum, and is also known by that same common. Another common name is the Branching Tree Anemone.

The Megalactis genus is a unique group of anemones that look more like colonies of soft corals than actinides. Typically they have an oral disc that is drawn out into branched tentacles tipped with white swellings, resembling globular spheres. They are found on coral rich slopes and drop-offs with coral gravel, or in shallow, sandy and muddy areas. They bury their foot and body into the substrate and adhere their foot to hard surfaces underneath, having only their oral disc and tentacles emerging. When disturbed they can retract their entire body into the sand and be virtually invisible.

Obtaining a Bali Fire Anemone, or any of the 'stinging sea anemones,' needs to be done only when you have enough knowledge to protect yourself and your other charges. These anemones have a very different look from anything that is typically sold, they are very poisonous, and the sting is very painful. A sting from these anemones can damage, and even kill, other corals and fish. Keeping them in a species specific tank allows you and them to be happy.

For more about the types of Sea Anemone Species, see:
Sea Anemone - Tube Anemone

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Bali Fire Anemone - Quick Aquarium Care
  • Minimum Tank Size: 50 gal (189 L)
  • Aquarist Experience Level: Intermediate
  • Temperament: Aggressive
  • Temperature: 75.0 to 82.0° F (23.9 to 27.8° C)
  • Size of organism - inches: 12.0 inches (30.48 cm)
  • Diet Type: Carnivore
  • Suitable for Nano Tank: No

Habitat: Distribution / Background

The Bali Fire Anemone Megalactis hemprichii (syn: Megalactis hemprichi) was described by Ehrenberg in 1834. The Megalactis genus is a member of the Actinodendronidae Family and was also described by Hemprich and Ehrenberg in 1834. There are currently 3 accepted species in this genus, including Megalactis cornatus, Megalactis griffithsi, and Megalactis hemprichii (Megalactis hemperichi). A fourth species, Megalactis annulata (nomen dubium), has an uncertain taxonomical significance due to no type and the original description being very vague.

The Megalactis genus is found in the Red Sea and the tropical Indo-Pacific Ocean; the Philippines, Taiwan, Papua New Guinea, and the Great Barrier Reef. The Bali Fire Anemone M. hemprichii is found in the Red Sea and in Indonesia, the Philippines. Megalactis hemprichii is not on the IUCN Red List for endangered species. Other names this genus of anemones are known by are Hell's Fire Anemone, Stinging Anemone, Tree Anemone, Branching Tree Anemone, Branching Anemone, and Branched Anemone

The Megalactis anemones have been found at depths ranging from 30 to 100 feet (9 - 31 m) in various habitats. One habitat is on slopes or vertical drop offs that are rich with corals and rock, having a gravel substrate. These areas are susceptible to occasional surges of water. Another habitat is in shallow waters with muddy or sandy substrate, that is protected from intense water movement. So they are pretty adaptable. Bali Fire Anemone M. hemprichii is found dwelling similar water conditions and habitats as other species, but at shallower depths, from 0 to 66 feet (0 - 20 meters).

All the Megalactis anemones bury their foot and body into the substrate and adhere their foot to hard surfaces underneath, having only their oral disc and tentacles emerging. When disturbed they can retract their entire body into the sand and be virtually invisible. They use their very powerful and venomous cells, the nematocyst found in their tentacles, to catch prey and also to sting and deflect any possible threats or attacks. These anemones feed on zooplankton and other small tidbits that cross their path, using their tentacles to stun and pull the morsels into their mouths. It is unknown if they have any predators, but they have been known to sting divers quite badly.

  • Scientific Name: Megalactis hemprichi
  • IUCN Red List: NE - Not Evaluated or not listed


The Bali Fire Anemone can grow up to 12" (30 cm). Other Megalactis anemones vary, but a typical size is around 9 or 10" (25 - 30 cm). It is unknown how long they live, in fact some anemones can be hundreds of years old in the wild. In captivity their lifespan is sharply curbed, yet some anemones have been known to last 100 years or more.

The color of the Bali Fire Anemone can be cream to brown, green or tan. They have a muscular pedal column with a sticky “foot” at the bottom to help keep them in place. They bury the foot into the substrate, or, depending on the individual, connect to a hard surface in between rocks like other anemones. They also use this foot to move around if conditions are not ideal.

Cylindrical, smooth tentacles branch radially from the oral disk. Along each side of the tentacles are small "branchlets," with groups of smaller “branched” tentacles extending from these. The smaller branched tentacles have sort of a ball-like shape at the tips. Other species have the small branchlets arranged in a straight line on the main tentacle. The tree-like shape that the Bali Fire Anemones have is very unique and makes them stand apart from other anemones.

There is a mouth opening in the center of the oral disc to take in food and expel waste. The mouth should be closed and tight, and will open when hungry, having an oval look; yet a gaping mouth is a warning signal. They use their very powerful and venomous cells or nematocysts found in their tentacles to sting and deflect any possible threats or attacks, as well as for capturing prey.

  • Size of organism - inches: 12.0 inches (30.48 cm) - Other Megalactis species vary in size.
  • Lifespan: 100 years - Less in captivity.

Difficulty of Care

The Megalactis genus can be moderate to care for yet, they do have lighting needs and must be in a large enough aquarium to satisfy their ultimate size. Putting an anemone in a new tank will result in failure. The tank should be at least 4 months old, though 9 t0 12 months is better, and stable before adding your new M. hemprichii anemone. They are best kept in a species specific tank.

When choosing a Bali Fire Anemone, make sure the color is good, their mouth is not gaping open, and their foot and tentacles are sticky to the touch. Also, they should be attached to something and make sure there is no damage to the foot area, often a result of pulling the anemone off its surface.

They are very poisonous and the sting is very painful, so aquarists be warned and wear gloves when handling this genus. To transfer a Bali Fire Anemone from another aquarium, use a very thin blunt item, like a credit card, to get under the foot. Slowly nudging it away will get the anemone off the glass. If its attached to a rock, ideally you can simply purchase the rock as well.

  • Aquarium Hardiness: Moderately Difficult
  • Aquarist Experience Level: Intermediate

Foods and Feeding

The Bali Fire Anemone is a carnivore and will generally accept small meaty foods in captivity. Feed the anemone chopped silversides, shrimp, krill and mussels, and fresh chopped fish (from your grocery store), as well as frozen carnivore preparations. To keep it healthy, feed twice a week. The old adage that anemones should only be fed once a month is false and has lead to many deaths.

  • Diet Type: Carnivore
  • Flake Food: Occasionally - Depends on individual tastes of the anemone.
  • Tablet / Pellet: Occasionally - Depends on individual tastes of the anemone.
  • Live foods (fishes, shrimps, worms): Some of Diet - From marine sources as a treat.
  • Liquid Foods: Some of Diet - Liquid foods with larger zooplankton.
  • Meaty Food: All of Diet - Any and all marine flesh.
  • Feeding Frequency: Weekly - Feed 2 times a week to keep them healthy.

Aquarium Care

Water changes of 10% bi-monthly or 20% a month are typical. Monitor your water quality for your particular situation and adjust your water changes accordingly. Waste production created by your anemone can be calculated in inches. Basically, every inch of anemone is equal to an inch of fish, so an average sized Bali Fire Anemone of 12" produces a bioload equivalent to that of four 3" fish or two 6" fish.

Purigen and Poly-fiber are great products to help in maintaining water quality. Purigen is a synthetic polymer that removes soluble and insoluble impurities from water at an exceptionally high rate and capacity, helping to control ammonia, nitrites and nitrates. Poly-fiber can be cut and used in sumps, etc. A good protein skimmer is a must.

Although anemones are not as dependent on calcium as stony corals, magnesium and calcium is still needed to keep the pH and alkalinity stable and within the correct parameters. Additions of trace elements are suggested. Phosphates should be kept around 0.03 or less.

  • Water Changes: Bi-weekly - Water changes of 10% twice a month, or 20% a month are typical.
  • Calcium Levels: 380.0 - 450.0 ppm - Helps to balance alkalinity. Aim for 420, or 385 if you are using Seachem calcium.
  • Alkalinity Levels: 7.0 - 11.0 dKH - (2.5 to 3.9 meq/L) Aim for 10 dKH (3.5 meq/l) for reef tanks.
  • Magnesium Levels: 1,250.0 - 1,350.0 ppm - Check magnesium levels and adjust before using Calcium test.
  • Strontium Levels: 5.0 - 15.0 ppm - Aim for 8 ppm
  • Iodine Levels: - 030 to .060 ppm. Control is not recommended.

Aquarium Setup

The typical reef environment is what is needed for your Bali Fire Anemone. A mature 50-gallon tank that is at least 9 to 12 months old is advised to increase the successful life span of M. hemprichii. They are not suited for small nano tanks, since it is hard to keep water quality high and due to their ultimate size. They need live rock and a deep sandy or crushed coral substrate to bury themselves into.The Bali Fire Anemone will attach to a hard surface, even under the substrate, with the ability to retract.

They need high levels of lighting, like any anemone, and the water movement should be moderate. A good protein skimmer is a must. Once it is secured and settled, if it is happy it will stay put. If it isn't happy and is moving around, be sure to check your checking your lighting and water quality. Also, make sure you are feeding it adequately. With all anemones it's a good rule of thumb to have all of your pumps covered. Most good quality pumps have guards on them.

  • Minimum Tank Size: 50 gal (189 L)
  • Suitable for Nano Tank: No
  • Live Rock Requirement: Typical Amount
  • Substrate Type: Mix - Sand + Coral - They like a deep sandy or crushed coral substrate to bury themselves into.
  • Lighting Needs: Moderate - normal lighting - Lighting should be moderate to high (normal to strong).
  • Temperature: 75.0 to 82.0° F (23.9 to 27.8° C)
  • Specific gravity: 1.023-1.025 SG
  • Water Movement: Moderate
  • Water Region: All - It will settle where ever it is comfortable and happy.

Social Behaviors

The Bali Fire Anemones have a dangerous and powerful sting. They will sting and all nearby corals, fish, and the hand that feeds it! These are aggressive anemones because they can be mobile, although a contented anemone will often stay put once it has found a place to settle. If it starts moving around you need to check your aquarium parameters and feeding schedule to find out why it is unhappy.

After splitting, they will tolerate their own “clones,” but will kill other anemones. All anemones need to have their own space, otherwise there can be a "chemical" warfare between species. This will usually cause one to not eat, shrink and eventually die. Having excellent filtration and a large tank, (over 100 gallons) will usually allow 2 anemones at opposite ends to thrive. You can also build a natural blockade to help prevent them from wandering into each others "space".

These anemones are sometimes available to the aquarist, but should not be obtained for anything other than a species display tank. It has often been suggested to not put anemones in a reef environment since corals cannot move away from the stinging tentacles. Once you get your anemone situated and it has not moved for several months, it might be safe to add other corals.

Besides stinging corals, they will sting and kill small fish, including clownfish because Bali Fire Anemones do not host them. Invertebrates, like snails and starfish, will know to stay away from the anemone. However, a very large tank is needed since these animals will constantly run into this anemone and could eventually die from the sting. The Bali Fire Anemone will host a Harlequin Crab (Lissocarcinus spp.), which makes for an amusing display.

  • Venomous: Yes - The Bali Fire Anemone may roam and sting sessile corals.
  • Temperament: Aggressive
  • Compatible with:
    • Same species - conspecifics: Sometimes - They will only tolerate their own clones.
    • Anemones: Threat
    • Mushroom Anemones - Corallimorphs: Threat
    • Leather Corals: Threat
    • Zoanthids - Button Polyps, Sea Mats: Threat
    • Sponges, Tunicates: Threat
    • Shrimps, Crabs, Snails: Threat
    • Starfish: Threat
    • Feather Dusters, Bristle Worms, Flatworms: Threat
    • Clams, Scallops, Oysters: Threat
    • Crabs: Monitor - The Bali Fire Anemone will host Harlequin Crabs.
    • Snails: Threat
    • Sea Apples, Cucumbers: Threat
    • Urchins, Sand Dollars: Threat
    • Nudibranch, Sea Slugs: Threat
    • Copepods, Amphipods, Mini Brittle Stars: Threat
    • Stony Corals: Threat - is aggressive
    • Soft Corals: Threat - is aggressive

Sex: Sexual differences

No sexual difference in appearance is known.

Breeding / Reproduction

The Megalactis species have not been bred in captivity. Anemones in general can multiply by sexual and asexual means. One way is using fission, which is when they actually split in half from the foot or mouth to form a clone, although the clone is its own animal, similar to twins. They will also reproduce using male and female sex glands or find another anemone of the opposite sex. Both will release mature gametes into their digestive system, which is then released up and out through the mouth. After this spawning method, the zygote will develop into planktonic larvae or free floating in open waters. They will form tentacles, septa and a pharynx right before they settle into the reef with the mouth pointing upward, then will begin to grow into a new anemone.

  • Ease of Breeding: Unknown - Has not been bred in captivity.

Ailments / Diseases

Bali Fire Anemones are usually disease free. Problems are pretty minimal unless your lighting, water movement, feeding and/or water quality is low or inadequate. In that case, your anemone will detach to look for "better conditions." In general, if your anemone moves, it is not happy. This usually results in an unpleasant experience with a water pump.


The Bali Fire Anemone M. hemprichii is rarely available to aquarists, and only suggested for a species specific tank.


  • Animal-World References: Marine and Reef
  • Megalactis hemprichii Ehrenberg, 1834, WORMS World Registry of Marine Species
  • Megalactis hemprichii Ehrenberg, 1834, SeaLifeBase
  • Adorian Ardelean, Family Actinodendronidae, University of Kansas. Natural History Museum & Biodiversity Research Center, Referenced Online 2009 (
  • Adorian Ardelean and Daphne Gail Fautin, A new species of the sea anemone Megalactis (Cnidaria: Anthozoa: Actiniaria: Actinodendridae) from Taiwan and designation of a neotype for the type species of the genus, The Biological Society of Washington (

Author: Clarice Brough CFS
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