Small Rock Anemone

Glass Rose Anemone, Trumpet Anemone, Yellow Aiptasia

Small Rock Anemone, Aiptasia diaphana, Glass Rose Anemone, Trumpet AnemoneAiptasia diaphanaPhoto © Animal-World, Courtesy David Brough

Quick as a whip, the Small Rock Anemone will retract into its hole or crevice if it feels threatened!

The Small Rock Anemone Aiptasia diaphana is fast at disappearing if disturbed. But this quick maneuver is just one of its fast tricks. It is quite small, at only about 1.2" (3 cm) tall, but is also very fast at reproducing. The Aiptasia anemones are called "rock anemones" because they are found along rocky shorelines, and often dubbed "glass anemones" due to their bodies being somewhat translucent. This pretty rock anemone is also known as the Glass Rose Anemone, Trumpet Anemone, and Yellow Aiptasia.

Aiptasia anemones don't have a very good reputation with saltwater hobbyists. They 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 can reach plague proportions in the aquarium or a reef tank, wreak havoc on the other inhabitants. 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 invertebrates most affected by Aiptasia pests. Unless you are keeping Small Rock Anemones in a refugium to help control nutrients, they need to be removed as soon as possible. Once Aiptasia gets a foothold, manual removal to keep populations in check, may very well become an ongoing activity.

Despite a bad reputation in the saltwater aquarium industry, the Small Rock Anemone does have redeeming qualities in the scientific world. It is used extensively for studies on growth due to its re-generation properties. It is also being considered for use in medical treatments. A method of using its stinging cells in skin creams to deliver insulin to diabetics in a needle-free way is being explored. Other Aiptasia being used in various types of research include the Glass Anemone Aiptasia pulchella, and the Brown Glass Anemone Exaiptasia pallida.

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

Small Rock Anemone, Aiptasia diaphana

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Another pest anemone that comes in brown or pinkish

This is yet another anemone that is considered an undesirable addition to a reef tank! The Small Rock Anemone, also called the Rose Glass Anemone is slightly different from the standard Aiptasia in that it has more color, being brown to a pinkish brown instead of clear or gray. Whatever color it is, it needs to go! When you see one, do your best to get rid of it before it reproduces!

Small Rock Anemone - Quick Aquarium Care
  • Minimum Tank Size: 1 gal (4 L)
  • Aquarist Experience Level: Beginner
  • Temperament: Aggressive
  • Temperature: 68.0 to 86.0° F (20.0 to 30.0° C)
  • Size of organism - inches: 1.2 inches (3.05 cm)
  • Diet Type: Carnivore
  • Suitable for Nano Tank: Yes

Habitat: Distribution / Background

The Small Rock Anemone Aiptasia diaphana was described by Rapp in 1829. It has a very broad range, found in the Mediterranean and Canary Islands, Bali, Indo Pacific, Indonesia, Kenya, Philippines and the Red Sea..This species is not on the IUCN Red List for endangered species. Some other common names it is known by are Glass Rose Anemone, Trumpet Anemone, and Yellow Aiptasia.

The Aiptasia genus is a member of the Aiptasiidae family and currently contains 12 species. General common names all the various Aiptasia anemones are known by are Aiptasia, Glassrose Anemone, Rock Anemone, Devil's Plague, Aiptasia Anemone, Pest Anemone, and sometimes by this misspelling, Aptasia.

Aiptasia anemones are found in shallow waters along protected coasts and along intertidal rocky shorelines. They are found alone attached to rubble, live rock, dead corals, and other hard substrates. They will also form dense colonies in areas of shallow water, sometimes so dense they look like solid sheets. They occur in deep water too, where there is good tidal action.

The Small Rock Anemones are solitary and found at depths of 6 1/2 to 9 feet (2 - 3 m). They live on vertical walls in small quiet harbors and in large pools. They generally eat zooplankton, but will always accept other food particles. Predators include Peppermint Shrimp, most Butterflyfsh, and aiptasia eating nudibranchs.

  • Scientific Name: Aiptasia diaphana
  • IUCN Red List: NE - Not Evaluated or not listed


The Small Rock Anemone is quite small, only getting up to about 1.2" (3 cm) tall. It is unknown how long Aiptasia 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.

Aiptasia diaphana are somewhat translucent and generally occur in a brownish or pink to reddish color with lighter tentacle tips. Their coloring comes from an algae called zooxanthellae living in its tissues. Their body form is the polyp. It is composed of an elongated column with an oral disc on top that has a mouth in the center. There are elongated tapering tentacles positioned in narrow rings on the outer margin of the oral disc. If it feels threatened, quick as a whip, this anemone will rapidly retract its tentacles, becoming a very small ball, and it will retract into its hole or crevice.

The Small Rock 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. Aiptasia anemones 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. Often Aiptasia will simply opt to 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: 1.2 inches (3.05 cm)
  • Lifespan: - It is unknown how long Aiptasia can live.

Difficulty of Care

Small Rock 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 aiptasia 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.

The number of Small Rock Anemones 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. This anemone, as well as any species of Aiptasia, is generally regarded as a pest. 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 Small Rock Anemone is a carnivore, but these anemones are also equipped with nutritional alternatives for their well-being. In the wild Aiptasia 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: Occasionally
  • Tablet / Pellet: Occasionally
  • 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 Aiptasia, the more nutrients there are, the happier it 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 Small Rock 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 aiptasia anemones will survive. They prefer a low-to-moderate water movement, but any type of movement is fine, just not stagnant water.

Using aiptasia in refugiums to take out nutrients can be effective, yet it can also be risky if any parts of an aiptasia migrates to the main tank. In a refugium, use screening to prevent free floating aiptasia 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: Any - They will thrive in bright light, but even under poor lighting aiptasia anemones will survive.
  • Temperature: 68.0 to 86.0° F (20.0 to 30.0° C)
  • Specific gravity: 1.023-1.025 SG
  • Water Movement: Weak - Prefers a lower flow to moderate flow.
  • Water Region: All - This anemone attaches to hard surfaces.

Social Behaviors

The Small Rock Anemones are aggressive, and ideally, they are best kept in their own tank. They have strong stings that can harm, and even kill other corals and fish. 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. They can be preyed upon by Peppermint Shrimp, most Butterflyfsh and aiptasia eating 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 aiptasia anemones is fairly easy, just feed it and it will multiply. Anemones in general can multiply by sexual and asexual means. Aiptasia 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.

Aiptasia anemones will tolerate their own “clones”, 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

Small Rock 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 Aiptasia then becomes the problem.

Regular and time consuming manual removal is often required so that an aquarium is not overrun by dense populations of Aiptasia. There are various ways to reduce and control aiptasia populations. Sea anemone predators provides a natural, biological method of controlling and possibly eliminating Aiptasia 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 Aiptasia removal and control, see: Aiptasia Pests - Getting Rid of Glass Anemones.


Saltwater aquarists don't usually buy 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.


Author: Clarice Brough CFS
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