Animal Diversity Web

Ge­o­graphic Range

Known as ei­ther Clark’s anemone­fish or yel­low­tail clown­fish, this species is the most widely dis­trib­uted anemone­fish in the Indo West Pa­cific, rang­ing from the Per­sian Gulf to west­ern Aus­tralia, through­out the Indo-Aus­tralian Arch­i­pel­ago, Melane­sia, and Mi­crone­sia, and as far north as Tai­wan, south­ern Japan, and the Ryukyu Is­lands. (Allen, 1997)

• Biogeographic Regions
• indian ocean
  • native
• pacific ocean
  • native

Habi­tat

Clark's anemone­fish in­habit coral reefs, shel­tered la­goons, and steep edges of reefs up to a depth of 60 me­ters. This species is al­ways found liv­ing within the ten­ta­cles of sea anemones (Class An­tho­zoa). Al­though they are often found near anemones such as En­tac­maea quadri­color, Het­er­ac­tis mag­nifica, and Sti­chodactyla gi­gan­tea, they are known to nat­u­rally as­so­ci­ate with all 10 of the anemone species known to host clown­fishes. (Allen, 1997; Fautin and Allen, 1992)

• Habitat Regions
• tropical
• saltwater or marine

• Aquatic Biomes
• reef

• Range depth

  1 to 60 m

  3.28 to 196.85 ft

Phys­i­cal De­scrip­tion

Clark’s anemone­fish are col­or­ful, al­though the exact pat­tern shows con­sid­er­able ge­o­graph­i­cal vari­a­tion. The base body color is usu­ally black but may range from a yel­low to brown color, with vary­ing amounts of or­ange on the head, ven­tral areas, and fins. A ver­ti­cal, white to yel­low­ish bar is lo­cated on the head, pos­te­rior to the eye, with two more on the body: one above the anus and the other at the base of the cau­dal fin. How­ever, ju­ve­niles from all ge­o­graphic re­gions and adults from Van­u­atu and New Cale­do­nia may be mainly or en­tirely or­ange-yel­low with only the two most an­te­rior white bars. The cau­dal fin may be white or yel­low, but is al­ways lighter than rest of body col­oration. Male cau­dal fins are ei­ther yel­low or white with yel­low edges, whereas in some fe­males, the cau­dal fin may change to a solid white as they ma­ture. Both males and fe­males have yel­low pec­toral fins. In­di­vid­u­als that re­side within Sti­chodactyla merten­sii are fre­quently black ex­cept for a pale snout, with white bars on the head and body, and a yel­low or white tail. Col­oration may dif­fer in ad­di­tional ways, de­pend­ing on the species of host anemone that the fish in­hab­its. (Allen, 1997; Fautin and Allen, 1992)

This species has a total of 10 dor­sal spines, 15 to 16 soft dor­sal rays, 2 anal spines, and 13 to 14 total anal soft rays. The teeth are close-set, each re­sem­bling a typ­i­cal in­cisor. These are used to de­fend its host anemone from in­vad­ing fish, and can in­flict harm to hu­mans if the fish is pro­voked. (Allen, 1997; Fautin and Allen, 1992)

On rare oc­ca­sions, these anemone­fish will de­velop an in­ter­est­ing mu­ta­tion within their eyes. A pale blue cres­cent will ap­pear in the upper part of the iris, often re­ferred to as “Pearl Eyes.” In­di­vid­u­als with this trait are highly de­sir­able within the aquar­ium trade. (Allen, 1997; Fautin and Allen, 1992)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Range length

  14 (high) cm

  5.51 (high) in

De­vel­op­ment

Eggs gen­er­ally hatch 6 to 8 days after fer­til­iza­tion, de­pend­ing on the sur­round­ing water tem­per­a­ture; the cooler the water, the longer the in­cu­ba­tion pe­riod. Once the eggs hatch, lar­vae are com­pletely in­de­pen­dent from their par­ents. The plank­tonic lar­val stage lasts be­tween 7 to 9 days and ends when the ju­ve­nile fish re­turns to the bot­tom and finds a suit­able host anemone to in­habit. (Breder and Rosen, 1966; Fautin and Allen, 1992; Fricke and Fricke, 1977; Myers, 1999; Thresher, 1984)

Re­pro­duc­tion

Clark's anemone­fish, as part of the anemone­fish sub­fam­ily Am­phipri­on­i­nae, is a species char­ac­ter­ized by protan­drous her­maph­ro­dism, mean­ing that all lar­vae de­velop as males and pos­si­bly change into fe­males later in life. An adult male, fe­male, and sev­eral ju­ve­niles may re­side to­gether within an anemone. If the fe­male is re­moved or dies, the largest male be­comes a fe­male. Fe­males con­trol males with ag­gres­sive dom­i­nance, thus pro­hibit­ing the cre­ation of other fe­males. The largest male will in turn dom­i­nate the ju­ve­niles, pre­vent­ing other males from spawn­ing. This re­sults in dis­tinct monog­a­mous pair­ings dur­ing the breed­ing sea­son. (Breder and Rosen, 1966; Fricke and Fricke, 1977; Myers, 1999)

Prior to spawn­ing, males pre­pare a nest where the fe­male de­posits her eggs. When spawn­ing is about to occur, the male, ex­tend­ing his fins in a cor­ralling ges­ture, chases the fe­male into the nest. The fe­male makes sev­eral passes over the nest and then be­gins to lay or­ange el­lip­ti­cal shaped eggs over a pe­riod of 1 to 2 hours be­fore leav­ing the nest. The male then passes over the eggs and fer­til­izes them. (Breder and Rosen, 1966; Thresher, 1984)

• Mating System
• monogamous

Clark's anemone­fish breed nearly year-round in trop­i­cal wa­ters, typ­i­cally spawn­ing 2 to 3 times per month. Spawn­ing fre­quency may be some­what lim­ited dur­ing win­ter months in the north­ern edge of its dis­tri­b­u­tion. Fe­males lay de­m­er­sal eggs (ad­her­ing to the sub­strate) in a large nest con­tain­ing of 600 to 700 el­lip­ti­cal eggs from mul­ti­ple spawn­ings. The eggs are ap­prox­i­mately 3 to 4 mm in length and are at­tached to the sub­strate with a fine thread. The num­ber of eggs in a nest varies de­pend­ing on the age and size of the fe­male. (Breder and Rosen, 1966; Fautin and Allen, 1992; Moyer, 1980; Thresher, 1984)

Spawn­ing is syn­chro­nized with the full moon and usu­ally oc­curs in the early morn­ing hours. Pos­si­ble ex­pla­na­tions for this in­clude stronger water cur­rents along the reef cre­ated by spring tides, which aid dis­per­sal by trans­port­ing the anemone­fish lar­vae greater dis­tances, and a greater food sup­ply and in­creased vis­i­bil­ity of plank­tonic prey as a re­sult of si­mul­ta­ne­ous spawn­ing of in­ver­te­brates (such as corals and an­nelids) dur­ing the full moon. (Breder and Rosen, 1966; Thresher, 1984)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sequential hermaphrodite
  • protandrous
• sexual
• fertilization
  • external
• oviparous

• Breeding interval

  Breeding occurs possibly 2 to 3 times per month, although spawning may be reduced (or cease completely) in the northern regions of their distribution during winter months.

• Breeding season

  Spawning occurs year-round in the tropics, but only in the warmer months (May-October) in northern regions. Spawning occurs near the full moon.

• Range number of offspring

  600 to 700

• Range time to hatching

  6 to 8 days

Males pro­vide the ma­jor­ity of egg care, with the fe­male in­volved only spo­rad­i­cally. Main du­ties of the male in­clude fan­ning the eggs in a process that helps with in­cu­ba­tion, and eat­ing eggs that are in­fer­tile or that have been dam­aged dur­ing spawn­ing. Once the eggs hatch, lar­vae are com­pletely in­de­pen­dent from their par­ents. (Thresher, 1984)

• Parental Investment
• male parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • male

Lifes­pan/Longevity

Data on longevity in wild Clark's anemone­fish is lim­ited to a sin­gle study, which es­ti­mated that a fe­male under pe­ri­odic ob­ser­va­tion over a pe­riod of 11 years was at least 13 years old at the time she dis­ap­peared from her host anemone, with other anemones host­ing fe­males with es­ti­mated ages of 10 and 12 years. Sex­u­ally func­tional males dis­ap­pear from anemones more fre­quently, per­haps sug­gest­ing shorter av­er­age lifes­pans for males, al­though this pat­tern could also be due to in­creased mo­bil­ity of males seek­ing dom­i­nance on other anemones. (Fautin and Allen, 1992; Moyer, 1986)

• Range lifespan
  Status: wild

  10 to 13 years

Be­hav­ior

Clark's anemone­fish form sym­bi­otic re­la­tion­ship with at least 10 dif­fer­ent anemone species. Since these fish are poor swim­mers and are sus­cep­ti­ble to pre­da­tion, they are com­pletely de­pen­dent upon the anemone for shel­ter and pro­tec­tion of their nests. In re­turn, anemones with a host fish pre­sent are typ­i­cally health­ier, pos­si­bly due to the anemone­fish’s con­sump­tion of par­a­sites or in­creased water cir­cu­la­tion that males cre­ate while they care for eggs. Al­though anemone­fishes are pro­tected from the sting­ing ne­ma­to­cysts found on the anemone by a thin layer of mucus that cov­ers their bod­ies, there is a pe­riod of ac­clima­ti­za­tion that must occur be­fore the fish be­comes im­mune to the anemone sting. This oc­curs as the fish swims over the anemone, rub­bing its belly and ven­tral fins on the ends of the ten­ta­cles until the fish be­gins pro­duc­ing the pro­tec­tive mucus cov­er­ing. (Fautin and Allen, 1992; Lee, 2011; Myr­berg and Fuiman, 2002)

A ju­ve­nile's search for an ideal host anemone is often a dif­fi­cult process, since Clark's anemone­fish are ag­gres­sive to other species, par­tic­u­larly when de­fend­ing a host anemone from con­geners. Fish in each anemone have an es­tab­lished dom­i­nance hi­er­ar­chy that keeps in­di­vid­u­als at a spe­cific so­cial rank. A newly-re­cruited ju­ve­nile is at the bot­tom of the hi­er­ar­chy and re­ceives the harsh­est ag­gres­sion when it en­ters an anemone com­mu­nity. Some ju­ve­niles may be dri­ven away, leav­ing them ex­posed and vul­ner­a­ble to pre­da­tion. (Bus­ton, 2003; Thresher, 1984)

• Key Behaviors
• natatorial
• diurnal
• motile
• sedentary
• territorial
• social
• dominance hierarchies

Home Range

Since this species is com­pletely de­pen­dent upon anemones for shel­ter, they never stray far from their re­spec­tive host anemone. Home range and ter­ri­tory is es­sen­tially the area within the ten­ta­cles of the host anemone. (Fautin and Allen, 1992)

Com­mu­ni­ca­tion and Per­cep­tion

Hi­er­ar­chi­cal so­cial struc­ture is main­tained through an array of ag­gres­sive tac­tics by larger fish to­wards the smaller in­di­vid­u­als re­sid­ing in the host anemone. Ju­ve­nile Clark's anemone­fish are able to find host anemones through ol­fac­tory im­print­ing that oc­curs as the eggs de­velop in the nest. Anemone se­lec­tion oc­curs as a rit­u­al­is­tic swim­ming pat­tern in which the fish will re­peat­edly brush up against the ten­ta­cles of the po­ten­tial host anemone. If the anemone is found to be un­suit­able in some way, the fish will move on to an­other anemone and re­peat the process until a suit­able host is found. Spe­cial chem­i­cals con­tained within the mucus layer cov­er­ing the skin of the clown­fish have the ca­pac­ity to block stings from the anemone’s ne­ma­to­cysts. (Fautin and Allen, 1992; Myers, 1999; Thresher, 1984)

Clark's anemone­fish are able to per­ceive their en­vi­ron­ment using vi­sual, ol­fac­tory, tac­tile, au­di­tory, and vi­bra­tional (lat­eral line) sen­sory sys­tems. (Fautin and Allen, 1992)

• Communication Channels
• visual
• tactile

• Perception Channels
• visual
• tactile
• acoustic
• vibrations
• chemical

Food Habits

This species pri­mar­ily con­sumes plank­tonic food such as zoo­plank­ton, cope­pods, and algae. In some cases, they have been ob­served to con­sume par­a­sites found on their host anemone. Feed­ing be­hav­ior is af­fected by the hi­er­ar­chi­cal struc­ture of the group within the host anemone. Smaller fish, which ex­pe­ri­ence the great­est amount of ag­gres­sion, have less en­ergy to ven­ture out­side the anemone to for­age, thus forc­ing them to re­main within a close dis­tance to their host. This may be ben­e­fi­cial to the over­all sur­vival of the pop­u­la­tion, as those smaller fish are bet­ter pro­tected from the pre­da­tion that the older and larger dom­i­nant fish are sub­jected to while for­ag­ing a few me­ters from their host anemone. (Fautin and Allen, 1992; Myers, 1999; Nose, 1985; Sano, et al., 1984; Thresher, 1984)

• Primary Diet
• omnivore
• planktivore

• Animal Foods
• eggs
• aquatic crustaceans
• zooplankton

• Plant Foods
• algae

• Other Foods
• microbes

Pre­da­tion

Lar­val anemone­fish are ex­tremely sus­cep­ti­ble to pre­da­tion as they are small, poor swim­mers, re­sult­ing in very high mor­tal­ity rates while in the plank­tonic stage. Pre­da­tion on adult and ju­ve­nile anemone­fishes is greatly re­duced due to the pro­tec­tion con­ferred by the host anemone, whose sting de­ters po­ten­tial preda­tors. The eggs are more sus­cep­ti­ble to pre­da­tion, mainly by wrasses and po­ma­cen­trid dam­selfishes. Egg pre­da­tion in­creases at night, when the male is not guard­ing them. (Thresher, 1984)

• Known Predators

  • wrasses (Labridae)
  • damselfishes (Pomacentridae)
  • sharks (Chondrichthyes)
  • sting rays (Myliobatidae)
  • brittle stars (Ophiotrichidae)

Ecosys­tem Roles

Clark's anemone­fish form mu­tu­al­is­tic sym­bi­otic re­la­tion­ships with all anemone species that are known to host anemone- and clown­fishes. In this re­la­tion­ship, the anemone­fish re­ceives shel­ter and a pro­tected nest­ing lo­ca­tion, while the host anemone re­ceives de­fense from its res­i­dent anemone­fishes. Anemones re­main health­ier while host­ing anemone­fish, de­vel­op­ing ter­mi­nal bulbs on the tips of the ten­ta­cles and thereby in­creas­ing the amount of sur­face area from which the pho­to­syn­thetic algae housed within the anemone’s ten­ta­cles can cap­ture solar en­ergy. These bulbs do not de­velop in anemones lack­ing anemone­fish. (Fautin and Allen, 1992; Gud­geon, 2011; Lee, 2011)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Clark's anemone­fish are found in the trop­i­cal fish aquar­ium trade and cer­tain rare color morphs of the species are highly sought after. They are eas­ily bred and grow rel­a­tively quickly in cap­tiv­ity, and thus make use­ful re­search an­i­mals. (Sadovy and Vin­cent, 2002; Thresher, 1984)

• Positive Impacts
• pet trade
• research and education

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There are no known neg­a­tive im­pacts of this species on hu­mans. Adults may nip at a SCUBA diver's fin­gers, if pro­voked.

• Negative Impacts
• injures humans
  • bites or stings

Con­ser­va­tion Sta­tus

Al­though the con­ser­va­tion sta­tus of this species has not been eval­u­ated, the in­creased de­mand for Clark's anemone­fish in the aquar­ium trade has re­duced pop­u­la­tions in some lo­ca­tions. As global de­gre­da­tion of coral reefs con­tin­ues to in­crease, these anemone­fish will un­doubtably en­counter de­creases in suit­able habi­tat avail­abil­ity, which may cause pop­u­la­tions to be­come threat­ened in the fu­ture. ("2003 IUCN Red List of Threat­ened Species", 2003)

• IUCN Red List

  Not Evaluated

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Other Com­ments

This species makes an ex­e­cel­lent choice as an aquar­ium fish for hob­bists who want a healthy and pro­duc­tive sym­botic clown­fish/anemone re­la­tion­ship due to its ver­sa­til­ity in adapt­ing to var­i­ous host anemones.

Con­trib­u­tors

Pad­gette' Steer (au­thor), San Diego Mesa Col­lege, Paul De­twiler (ed­i­tor), San Diego Mesa Col­lege, Je­remy Wright (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

IUCN. 2003. "2003 IUCN Red List of Threat­ened Species" (On-line). Ac­cessed Oc­to­ber 04, 2011 at www.​iucnredlist.​org..

Allen, G. 1997. Ma­rine Fishes of Trop­i­cal Aus­tralia and South-East Asia. Perth, Aus­tralia: West­ern Aus­tralian Mu­seum.

Breder, C., D. Rosen. 1966. Modes of re­pro­duc­tion in fishes. Nep­tune City, New Jer­sey: T.F.H. Pub­li­ca­tions.

Bus­ton, P. 2003. Forcible Evic­tion and Pre­ven­tion of Re­cruit­ment in the Clown Anemone­fish. Be­hav­ioral Ecol­ogy, 14.4: 576-582.

Fautin, D., G. Allen. 1992. Field Guide to Anemone­fishes and their Host Sea Anemones. Perth, Aus­tralia: West­ern Aus­tralian Mu­seum. Ac­cessed No­vem­ber 01, 2011 at http://​www.​nhm.​ku.​edu/​inverts/​ebooks/​intro.​html.

Fricke, H., S. Fricke. 1977. Monogamy and sex change by ag­gres­sive dom­i­nance in coral reef fish. Na­ture, 266: 830-832.

Gud­geon, R. 2011. "Tongue-eat­ing louse par­a­sitiz­ing striped anemone­fish" (On-line). Ac­cessed De­cem­ber 20, 2011 at http://​www.​tumblr.​com/​tagged/​amphiprion+clarkii.

Lee, R. 2011. Nu­tri­tional Ex­change in a Trop­i­cal Tri­par­tite Sym­bio­sis: Di­rect Ev­i­dence for the Trans­fer of Nu­tri­ents from Anemone­fish to Host Anemone and Zoox­an­thel­lae. Ma­rine Bi­ol­ogy, 158.3: 589-602.

Moyer, J. 1986. Longevity of the anemone­fish Am­phiprion clarkii at Miyake-jima, Japan with notes on four other species.. Copeia, 1986: 135-139.

Moyer, J. 1980. In­flu­ence of Tem­per­ate Wa­ters on the Be­hav­ior of the Trop­i­cal Anemone­fish Am­phiprion Clarkii at Miyake-Jima, Japan. Bul­letin of Ma­rine Sci­ence, Vol. 30, Sup­ple­ment 1: 261-272.

Myers, R. 1999. Mi­cone­sian Reef Fish: A Field Guide for Divers and Aquar­ists. Bar­ri­gada, Ter­ri­tory of Guam: Coral Graph­ics.

Myr­berg, A., L. Fuiman. 2002. The Sen­sory World of Coral Reef Fishes. Pp. 146 in P Sale, ed. Coral Reef Fishes: Dy­nam­ics and Di­ver­sity in a Com­plex Ecosys­tem. San Diego, CA: Aca­d­e­mic Press.

Nose, Y. 1985. Food habits of teleostean reef fishes in Ok­i­nawa Is­land, South­ern Japan. Tokyo, Japan: Uni­ver­sity of Tokyo Press.

Sadovy, Y., A. Vin­cent. 2002. Eco­log­i­cal Issue and the Trade in Live Reef Fishes. Aca­d­e­mic Press, San Diego, CA, Coral Reef Fishes: Dy­nam­ics and Di­ver­sity in a Com­plex Ecosys­tem: 395.

Sano, M., M. Shimizu, Y. Nose. 1984. Food habits of teleostean reef flshes in Ok­i­nawa Is­land, south­ern Japan. Univ. Mus., Univ. Tokyo, Bull. 25: 1-128.

Steene, R. 1988. Fishes of Christ­mas Is­land, In­dian Ocean. Christ­mas Is­land Nat­ural His­tory As­so­ci­a­tion, Christ­mas Is­land, In­dian Ocean, 6798: 197.

Thresher, R. 1984. Re­pro­duc­tion in Reef Fishes. New Jer­sey: T.F.H. Pub­li­ca­tions, Inc..