The Brown Glass Anemone may not be a hero in the reef tank, but it has a claim to fame in the world of research!

The Brown Glass Anemone Exaiptasia pallida (previously Aiptasia pallida) is a very hardy animal that can reproduce quickly in a stable environment. It is a hermatypic anemone, meaning that it contains and depends upon zooxanthellae (algae) for nutrients. This makes it very durable and easy to maintain.

This is one of the rock anemones whose fame is in its contribution to the understanding of coral bleaching. Along with the Glass AnemoneAiptasia pulchella, it is being used in experimental modeling studies to understand how the stress of increased water temperatures affects this symbiotic relationship. Hopes are to learn how environmental causes of bleaching are linked to climate change and disease. Other rock anemones being used in various types of research include the Small Rock AnemoneAiptasia diaphana. Other common names it is know by are Glass Anemone, Rock Anemone, and Yellow Anemone.

Small glass anemones don’t have a very good reputation with saltwater hobbyists, and this Pale Glass Anemone is no exception. A number of scientific studies have determined that the Glass Anemones have strong stings, and don’t “play nice†with other corals and fish. They use venomous cells, nematocyst found in their tentacles, to sting corals and fish. They are very hard to get rid of and have been known to take over a reef aquarium by quickly reproducing while stinging and killing other tank invertebrates.

The Brown Glass Anemone can reach plague proportions in captivity. They are very hard to get rid of and have been known to take over a reef aquarium by quickly reproducing while stinging and killing other tank invertebrates. Corals and other anemones are the most affected by this pest. This anemone needs to be removed as soon as possible. Once it gets a foothold, manual removal to keep populations in check, may very well become an ongoing activity.

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

Brown Glass Anemone, Aiptasia pallida

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Awesome video of Peppermint Shrimp eating this pest anemone

Brown Glass Anemones will quickly become the scourge of a captive environment! There are True Peppermint Shrimp that will eat this pest, however if they have plenty of other foods to choose from, they may not be as affective. These anemones will reproduce like rabbits, sting corals and fish and make a new aquarist just give up! Quarantining live rock and all new corals is the best prevention since these little buggers can slip and hide into the smallest opening under a coral edge or in any rock!

  • Kingdom: Animalia
  • Phylum: Cnidaria
  • Class: Anthozoa
  • Order: Actiniaria
  • Family: Aiptasiidae
  • Genus: Exaiptasia
  • Species: pallida
Brown Glass Anemone – Quick Aquarium Care
  • Minimum Tank Size: 1 gal (4 L)
  • Aquarist Experience Level: Beginner
  • Temperament: Aggressive
  • Temperature: 68.0 to 83.0° F (20.0 to 28.3&deg C)
  • Size of organism – inches: 2.0 inches (5.08 cm)
  • Diet Type: Carnivore
  • Suitable for Nano Tank: Yes

Habitat: Distribution / Background

The Brown Glass Anemone Exaiptasia pallida (previously Aiptasia pallida) was described by Agassiz in Verrill, in 1864. It is found in the Western Atlantic Ocean in the coastal ranges of southern United States Atlantic and Gulf coasts, ranging from North Carolina to Texas, as well as the coastal Caribbean. This anemone is not on the IUCN Red List for endangered species.

The Brown Glass Anemone is also commonly known as the Pale Anemone. A few other common names it is known by are Glass Anemone, Rock Anemone, and Yellow Anemone. It was previously a member of the Aiptasia genus, but then moved to a new genus, Exaiptasia, which was created by Grajales & Rodriguez in 2014. The Exaiptasia genus is a member of the Aiptasiidae family and currently contains just this one species. General common names this species, and all the various Aiptasia anemones are known by, include Aiptasia, Glassrose Anemone, Rock Anemone, Devil’s Plague, Aiptasia Anemone, Pest Anemone, and sometimes by this misspelling, Aptasia.

Brown Glass Anemones are generally found singly where there is hard substrata in shallow water. It is common around floating docks and oyster reefs as well as attached to stones in rubble areas, mangrove roots, dead corals, and other hard substrates. They will also form dense colonies in areas of shallow water. They generally eat zooplankton, but will always accept other foot particles. Predators include several species of butterflyfish, True Peppermint Shrimp and some species of nudibranchs.

  • Scientific Name: Exaiptasia pallida
  • IUCN Red List: NE – Not Evaluated or not listed


The Brown Glass Anemone can get up to about 2″ (5 cm) tall, but most specimens only reach about 1†(2.5 cm) tall. It is unknown how long Exaiptasia anemones can live, but they do reproduce quickly. Mature specimens can produce dozens of juveniles in a single day if they have plenty of nutrients.

The Exaiptasia pallida are somewhat translucent and occur in two colors, one is white and the other is a rich brownish-yellow. This may account for their two regularly used common names, Pale Anemone and Brown Glass Anemone. The color comes from an algae called zooxanthellae living in its tissues.

Their body form is the polyp. It is composed of a long, thin column with an oral disc on top that has a mouth in the center. There are 100 long stinging tentacles, alternating between long and shore, and positioned in narrow rings on the outer margin of the oral disc. The disc supporting these tentacles is only about 1 cm wide! If it feels threatened, quick as a whip, the Pale Anemone will rapidly retract its tentacles becoming a very small ball, and it will retract into its hole or crevice.

The Brown Glass Anemone, or Pale Anemone, has a pedal disc or ‘foot’ with which it attaches to the substrate. If tank conditions are not ideal they will use their “foot†to move along the substrate. They do this by contracting the circular muscles of the foot and pushing forward, or they may crawl on their side, moving about 4 cm per hour. Exaiptasia pallida will often opt to simply disconnect and float around, or swim by moving in a spiral motion, until they find a new spot to adhere too.

  • Size of organism – inches: 2.0 inches (5.08 cm) – Most specimens only reach about 1″ (2.5 cm) tall.
  • Lifespan: – Unknown

Difficulty of Care

Brown Glass Anemones are easy to care for and they are quite hardy and durable. They have the ability to reproduce rapidly in saltwater aquariums where there are plenty of nutrients and good lighting. Some aquarists use small rock anemones in their refugiums to take out nutrients from the water. Keeping them in a screened off area of the refugium, they will feed on excess nutrients, thus improving water quality.

This anemone, as well as any of the Aiptasia species, is generally regarded as a pest. The Brown Glass Anemone can reach plague proportions in captivity. In some aquariums they will reproduce faster than in others, but the exact reason is unknown. They do seem to reproduce faster in environments high in nutrients and detritus. They can be difficult to control and/or eliminate once they get a foothold.

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

The Brown Glass Anemone is a carnivore, but these anemones are also equipped with nutritional alternatives for their well-being. In the wild rock anemones derive nutrition from their symbiotic algae, zooxanthellae, as well as from the water around them. They use their tentacles to capture organic matter that floats by, then insert the food into their mouths for ingestion. They generally eat zooplankton, but will always accept other foot particles.

  • Diet Type: Carnivore
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Liquid Foods: Some of Diet
  • Meaty Food: All of Diet
  • Feeding Frequency: Daily

Aquarium Care

Do water changes of 10% monthly or 20% every other month. They will flourish in poor water-quality environments that are rich in organic nutrients. For most anemones, typical water changes are 10% twice a month or 20% a monthly, but with rock anemones, the more nutrients there are, the the happier they will be.

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: Monthly
  • Calcium Levels: 380.0 – 450.0 ppm – Helps to balance alkalinity. Aim for 420 ppm, or 385 ppm 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 – Test magnesium levels and adjust before checking Calcium.
  • Strontium Levels: 5.0 – 15.0 ppm – Aim for 8 ppm.
  • Iodine Levels: – .030 to .060 ppm: Control is not recommended.

Aquarium Setup

The Brown Glass Anemone is quite small, so it can readily be kept in a nano tank of just 1-gallon or more, however, the tank should be completely cycled. The typical reef environment is best for these anemones. Like most anemone species, they need live rock or some other solid material they can attach to.

Any substrate is fine as these anemones will inhabit all levels of the tank. They need the same type of lighting found in a typical reef, and moderate lighting is suggested. They will thrive in bright light, but even under poor lighting rock anemones will survive. Any type water movement, from a gentle current to a strong flow, works fine for them as well, just not stagnant water.

Using small rock anemones in refugiums to take out nutrients can be effective, yet it can also be risky if any parts of an anemone migrates to the main tank. In a refugium, use screening to prevent free floating rock anemones from migrating to your main tank. Be sure to have all of your pumps covered. Most good quality pumps have guards on them.

  • Minimum Tank Size: 1 gal (4 L)
  • Suitable for Nano Tank: Yes
  • Live Rock Requirement: Typical Amount
  • Substrate Type: Any
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 68.0 to 83.0° F (20.0 to 28.3&deg C) – Has been known to endure wider ranges of temperatures than these.
  • Specific gravity: 1.023-1.025 SG
  • Water Movement: Any – Not stagnant.
  • Water Region: All

Social Behaviors

The Brown Glass Anemones have strong stings that can harm, and even kill other corals and fish. Because they are aggressive, ideally, they are best kept in their own tank. Saltwater hobbyists don’t purchase these anemones, rather they are acquired accidentally as “hitch-hikers” on live rock or with other corals. They are very hard to get rid of and have been known to take over a reef aquarium.

They can reproduce quickly and will tolerate their own kind, but they are able to out compete other species in the reef tank. When disturbed they eject dangerous white stinging threads, or acontia. Also, by using the venomous cells, the nematocyst found in their tentacles, they sting and push other inhabitants away from their “turf.†They don’t host clownfish. Predators include several species of butterflyfish, True Peppermint Shrimp and some species of nudibranchs.

  • Venomous: Yes
  • Temperament: Aggressive
  • Compatible with:
    • Same species – conspecifics: Yes
    • 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: Threat
    • 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. However, studies of Exaiptasia pallida and Aiptasia pulchella have determined that individuals are dioecious, meaning that individuals are of separate sexes.

Breeding / Reproduction

Propagating rock anemones is fairly easy, just feed it and it will multiply. Anemones in general can multiply by sexual and asexual means. Rock anemones will multiply asexually by fission, which is where a tiny bit of tissue detached from the foot quickly develops into a new and complete anemone.

Brown Glass Anemones will tolerate their own “clonesâ€, and these anemones are very prolific. This is why it is very difficult to physically remove these anemones from a rock. Any remaining tissues quickly multiply into to new specimens. Sexual reproduction has not been described for the species.

  • Ease of Breeding: Easy

Ailments / Diseases

Brown Glass Anemones are durable and problems are pretty minimal unless your lighting, water movement, and feeding is inadequate. Then your anemone will detach to look for “better conditions.†With better conditions, they can quickly multiply. Having a quickly expanding population of rock anemones then becomes the problem.

Regular and time consuming manual removal is often required so that an aquarium is not overrun by dense populations of rock anemones. There are various ways to reduce and control rock anemone populations. Sea anemone predators provides a natural, biological method of controlling and possibly eliminating these anemones. Other methods include chemical removal and the more risky method of physical removal. There are important considerations when using either of these two methods.

For information on small rock anemone removal and control, see:Aiptasia Pests – Getting Rid of Glass Anemones.


Saltwater aquarists don’t usually buy Brown Glass Anemones, but Aiptasia is available alive from supply companies for research and scientific study. Aquarists generally acquire them as hitchhikers, arriving with live rock or attached to the base of corals.


Featured Image Credit: Vojce, Shutterstock