The Carpet Anemones are named for their immense size (sometimes more than a meter/yard across) and "pile" of numerous colored tentacles. These are unfortunately very difficult aquarium specimens that "shed", otherwise can/do sting and poison tankmates. Unless you have a HUGE system (hundreds plus gallons of water) and/or a substantial sized system to dedicate to just this one animal (plus possibly host fishes), you are advised to look elsewhere for an anemone species.
Of the three species of Carpets that are commensal/symbiotic with Clowns (and the Three-spot Damsel), only H. mertensii has good potential for being kept in a "mixed reef" setting... the other two species are found anchored in sand... with no other Cnidarians w/in physical or easy-chemical reach.
The following is offered as a guide in identifying and discerning the three Carpet Anemone species that are symbiotic with Clownfishes... there are some other "carpet-like" anemones, including one from the Atlantic... that are fish eaters.
Differentiating the Carpet Anemone Species:
A note re the nefarious practice of dying/dyed anemones... Some Carpets are sold as such, particularly S. haddoni... Blue, Red and Yellow carpets are most often dyed and most are not destined to live long for the stress of it all. Let the buyer beware.
A Mention of the Atlantic "Carpet Anemone", So You Can Recognize & Avoid It:
Mmmm, what to mention here? Do know that these anemones can/will move... and yes, this can be an utter disaster... Stinging, eating most any live thing it brushes against... getting caught against pump intakes, overflows... Do position yours in an area of sufficient illumination and feed it sufficiently...
Carpet Anemone/Clownfish Natural Symbiotic Relations: (After Fautin1997, 2006 and pers. obs.)
Other Clowns/Amphiprionine species may become associated under captive conditions... And the ones that are naturally symbiotic, tank bred and raised or wild-collected may not choose to form such associations at all... AND, very importantly, ALL Carpet Anemone species are fish eaters... and MAY consume novel Clowns and all other fish life... even hapless motile invertebrates... You have been warned.
Are Carpets compatible with other Anemones? In one word, no... They're generally the "winners" in such contests... but all may lose (die). Clones (hard to find... but can be made... see below)... Carpet Anemones can learn to get along with a wide range of other Cnidarian Classes species though... As a high-order stinger... this Anemone group of species (and most all others) are best placed last... after all other stinging-celled life has been placed (carefully out of reach at full expansion...) and become well-established.
The "usual suspects"... Triggerfishes, large puffers and big wrasses, the bigger marine angels and crabs... will have a go, tear up even a carpet anemone if hungry, bored or just curious. These should not be housed together.
The usual criteria apply for picking out a healthy Carpet Anemone... that the specimen is open (will likely greatly expand after acclimating... are "squeezed" down for shipping...), w/o apparent tears to the base, that the mouth not be totally gaping... And the acid-test for all marines: that it be feeding.
Newly arrived anemones are not a good idea to purchase... Put a deposit down and leave prospective buys at your dealers for a good week.
And do avoid "all-white" carpets... these are not healthy, but bleached specimens that have lost their natural endosymbiotic algae... and will very likely perish, rather than survive the span of time et al. it takes to reincorporate these symbionts.
Habitat, as per above... S. gigantea may be the most suitable of the carpets... being found often in very shallow water in the sand... sometimes exposed at low tide! It also is the most common species found amongst corals. S. gigantea Pedal discs attached to solid object. S. mertensii lives attached to hard substrate.S. haddoni, lives in deeper areas, cleaner sand. How much sand for a Haddon's? A good four inches plus of fine coral sand is about right.
How large a system will do? NOTHING under a few hundred gallons... As usual, the bigger the better... For expansion, growth, placing other life, aquascaping... Diluting wastes...
How much circulation is advised? Something short of ripping the animals off the rock, but complete and vigorous, non-linear... 20-30-40 times turnover is getting there. And one more time: ALL intakes must be thoroughly screened to protect against damaging your potentially roaming anemone...
Water quality? The best you can render... Oversized skimming, use of an ozonizer (with a desiccator if you can...)... Frequent partial water changes, a dearth of "additives"... testing for whatever you add of course. Any/all such supplements should be added to change and/or make-up water and thoroughly dissolved in the stored water ahead of use.
It cannot be re-stated enough times that the behavior of your livestock is the best indication of the suitability of its environment. KEEP your eye on your Anemone... IF it is shrinking down, everting its mouth, moving about... SOMETHING is amiss... perhaps your water quality is on a slide, maybe your lighting/lamps are getting old... ACT!
Thawed krill, shrimp silver sides, various "frutti de mar" are fine if foods if they are finely shredded. Feeding large whole prey that is larger than the mouth otherwise can be harmful to an anemone in the long run. Most meaty foods of ocean origins are fine (Pacifica plankton, Mysid shrimp, fish roe, etc). Terrestrial and freshwater foods should NOT be offered... they're not totally digestible, nor nutritious... Yes, this includes "feeder" goldfish here as well.
Some folks feed their carpets very infrequently (a few times to about twice a month) not wanting to experience too rapid growth. Do bear in mind if there are fishes present, and/or a thriving refugium with a DSB... they'll also get a fair amount of stray fish food and "fuge" foods. This being stated, there are folks who feed these "eager eating" animals a few times per day... There is some evidence that such frequent feedings do encourage aggressive feeding behavior (tankmates)...
Regurgitated food, and waste pellets of such should be promptly removed by vacuuming of netting.
Most all health issues can be traced to something awry with the environment... An imbalance of Calcium, other biomineral with alkalinity, too low RedOx, old phase and intensity shifted lighting... Develop a routine of checking your animals every time you go by their system... count all during feeding. Be keen to observe alls' behavior closely. There are few examples of "sudden loss" that was not preceded by "poor behavior" (Swollen, gaping, everted mouth... staying small/shrunken, losing attachment...) of these animals.
Carpet Anemones, by virtue of their large size, sometimes "sticky" nature and general lack of hardiness in captivity are not good candidates for asexual propagation (fragmentation, cutting...). But sometimes they do this themselves... in reaction to favorable and disfavored conditions... the former are generally instigated by a growth, doubling of the mouth, ahead of actual binary fission. Best to encourage yours to split by taking the best care of it you can.
Definitely not for everyone... Carpet Anemones ARE spectacular animals... But require large volumes, special treatment in terms of lighting, regular feedings... And MUST be accommodated in terms of other livestock... NO other anemones need apply for residency... All other Cnidarians need to be placed/located out of harms way... and ALL fishes are in danger of being consumed in time.
Do you have such a system available? The patience to cater to such a specimen? If you must have an anemone, you are STRONGLY advised to seek out a different species than a Carpet... Perhaps a nice (tank bred is far superior) Bubbletip (Entacmaea quadricolor) or Sebae (Heteractis crispa)... these are not easy to keep either, but are far more manageable in terms of their size, requirements and potential for consuming tankmates.
Fatherree, James. 2000. The killer carpet. The feeding habits of Stichodactyla haddoni in the reef aquarium. TFH 6/00.
Fatherree, James. 2002. Keeping Sea Anemones. What you need to know. TFH 12/02
Fautin, Daphne G. & Gerald R. Allen. 1992, revised ed. 1997. Anemone Fishes and Their Host Sea Anemones. Western Australian Museum. 160 pp.
Fautin, Daphne G. 2006. Hexacorallians of the World. http://geoportal.kgs.ku.edu/hexacoral/anemone2/index.cfm
Fenner, Robert. 1992. Anemones in captive systems. FAMA 10/92
Karli, Scott W. 2003. Sea Anemones. FAMA 1/03.
Shimek, Ronald L. 2002. Host Anemones. Responsible care will ensure their survival. AFM 10/03
Shimek, Ronald L. 2003. Anemone troubleshooting; With no defined life span, anemones may last indefinitely- but only if given proper care by an aquarist who researches their needs and meets their care requirements. AFM 10/03
Shimek, Ronald L. 2004. Are any Anemones right for beginners? In a stable tank, a couple species might work. AFM 3/04
Toonen, Rob. 2001. Invert Insights (column) Re: Anemones, Clownfish symbionts. TFH 9/01.
Toonen, Rob. 2003. Ask the Reefer (column). Gen. disc. re Anemones in captivity. TFH 3/03.