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Clown fish in the Andaman Coral Reef.jpg
Ocellaris clownfish, Amphiprion ocellaris
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Actinopterygii
Order: Perciformes
Family: Pomacentridae
Subfamily: Amphiprioninae

Amphiprion Bloch & Schneider, 1801
Premnas Cuvier, 1816

Ocellaris clownfish nestled in a magnificent sea anemone (Heteractis magnifica)
Clown fish swimming movements
A clownfish swimming.
Video of a clownfish swimming around an anemone.


Distribution and habitat[edit]

Clownfish are native to warmer waters of the Indian and Pacific oceans, including the Great Barrier Reef and the Red Sea. While most species have restricted distributions, others are widespread. Clownfish live at the bottom of shallow seas in sheltered reefs or in shallow lagoons.


Clownfish are omnivorous and can feed on undigested food from their host anemones, and the fecal matter from the clownfish provides nutrients to the sea anemone. Clownfish primarily feed on small zooplankton from the water column, such as copepods and tunicate larvae, with a small portion of their diet coming from algae, with the exception of Amphiprion perideraion, which primarily feeds on algae.[1][2] They may also consume the tentacles of their host anemone.[3]

Symbiosis and mutualism[edit]

Clownfish and sea anemones have a symbiotic, mutualistic relationship, each providing a number of benefits to the other. The individual species are generally highly host specific, and especially the genera Heteractis and Stichodactyla, and the species Entacmaea quadricolor are frequent clownfish partners. The sea anemone protects the clownfish from predators, as well as providing food through the scraps left from the anemone's meals and occasional dead anemone tentacles. In return, the clownfish defends the anemone from its predators, and parasites.[4][5] The anemone also picks up nutrients from the clownfish's excrement, and functions as a safe nest site.[6] The nitrogen excreted from clownfish increases the amount of algae incorporated into the tissue of their hosts, which aids the anemone in tissue growth and regeneration.[2] It has been theorized that the clownfish use their bright coloring to lure small fish to the anemone,[7] and that the activity of the clownfish results in greater water circulation around the sea anemone.[8] Studies on anemonefish have found that clownfish alter the flow of water around sea anemone tentacles by certain behaviours and movements such as "wedging" and "switching." Aeration of the host anemone tentacles allows for benefits to the metabolism of both partners, mainly by increasing anemone body size and both clownfish and anemone respiration.[9]


  • The coevolution of certain species of clownfish with specific anemone host species and may have acquired an immunity to the nematocysts and toxins of their host anemone. Experimentation has shown that Amphiprion percula may develop resistance to the toxin from Heteractis magnifica, but it is not totally protected, since it was shown experimentally to die when its skin, devoid of mucus, was exposed to the nematocysts of its host.[10]



In a group of clownfish, there is a strict dominance hierarchy. The largest and most aggressive female is found at the top. Only two clownfish, a male and a female, in a group reproduce through external fertilization. Clownfish are sequential hermaphrodites, meaning that they develop into males first, and when they mature, they become females. If the female clownfish is removed from the group, such as by death, one of the largest and most dominant males will become a female. The remaining males will move up a rank in the hierarchy.

Clownfish lay eggs on any flat surface close to their host anemones. In the wild, clownfish spawn around the time of the full moon. Depending on the species, clownfish can lay hundreds or thousands of eggs. The male parent guards the eggs until they hatch about six to ten days later, typically two hours after dusk.[citation needed]

Parental investment[edit]


The reproductive cycle of clownfish is often correlated with the lunar cycle. Rates of spawning for clownfish peak at approximately the first and third quarters of the moon. The timing of this spawn means that the eggs will hatch around the full moon or new moon periods. One explanation for this lunar clock is that spring tides produce the highest tides during full or new moons. Nocturnal hatching during high tide may reduce predation by allowing for a greater capacity for escape. Namely, the stronger currents and greater water volume during high tide protects the hatchlings by effectively sweeping them to safety. Before spawning, clownfish exhibit increased rates of anemone and substrate biting, which help prepare and clean the nest for the spawn.[15]


In the aquarium[edit]

Clownfish make up 43% of the global marine ornamental trade, and 25% of the global trade comes from fish bred in captivity, while the majority are captured from the wild,[18][19] accounting for decreased densities in exploited areas.[20] Public aquaria and captive breeding programs are essential to sustain their trade as marine ornamentals, and has recently become economically feasible.[21][22] It is one of a handful of marine ornamentals whose complete life cycle has been closed in captivity. Members of some clownfish species, such as the maroon clownfish, become aggressive in captivity; others, like the false percula clownfish, can be kept successfully with other individuals of the same species.[23]

When a sea anemone is not available in an aquarium, the clownfish may settle in some varieties of soft corals, or large polyp stony corals.[citation needed] Once an anemone or coral has been adopted, the clownfish will defend it. As there is less pressure to forage for food in an aquarium, it is common for clownfish to remain within 2-4 inches of their host for their entire lifetime.[citation needed] Clownfish, however, are not obligately tied to hosts, and can survive alone in captivity.[24][25]


In popular culture[edit]

In Disney/Pixar's 2003 film Finding Nemo, the main character is a clownfish. The species depicted in the film is A. ocellaris.[4] It will also appear in the upcoming sequel Finding Dory.



  1. ^ Fautin, Daphne; Gerald Allen (1997). Field Guide to Anemone Fishes and Their Host Sea Anemones (2 ed.). Perth, Australia: Western Australian Museum. ISBN 978-0-7309-8365-1. 
  2. ^ a b Porat, D.; Chadwick-Furman, N.E. (2005). "Effects of anemonefish on giant sea anemones: Ammonium uptake, zooxanthella content and tissue regeneration". Marine and Freshwater Behaviour and Physiology 29 (1): 43–51. doi:10.1080/10236240500057929. 
  3. ^ Fautin, D.G.; Guo, C.; Hwang, J.S. (1995). "Costs and benefits of the symbiosis between the anemoneshrimp Periclimenes brevicarpalis and its host Entacmaea quadricolor.". Marine Ecology Progress Series 129: 77–84. doi:10.3354/meps129077. 
  5. ^ Amphiprioninae at the Encyclopedia of Life
  8. ^ Szczebak, Joseph T.; Raymond P. Henry; Fuad A. Al-Horani; Nanette E. Chadwick (2013). "Anemonefish oxygenate their anemone hosts at night". Journal of Experimental Biology 216 (9): 970–976. doi:10.1242/jeb.075648. 
  9. ^ Joseph T. Szczebak, Raymond P. Henry, Fuad A. Al-Horani, Nanette E. Chadwick (2012-11-03). "Anemonefish oxygenate their anemone hosts at night". The Journal of Experimental Biology. Retrieved 2013-09-15. 
  15. ^ a b Robert M. Ross (1978-02-10). "Reproductive Behavior of the Anemonefish Amphiprion melanopus on Guam" (PDF). Copeia. Retrieved 2013-09-15. 
  17. ^ Swagat Ghosh, T. T. Ajith Kumar, T. Balasubramanian (2011-08-04). "Determining the level of parental care relating fanning behavior of five species of clownfishes in captivity" (PDF). Indian Journal of Geo-Marine Sciences. Retrieved 2013-09-15. 
  18. ^ Dhaneesh, K.V.; R. Vinoth; Swagat Gosh; M. Gopi; T.T. Ajith Kumar; T. Balasubramanian (2013). Sundaresan, J., ed. "Hatchery Production of Marine Ornamental Fishes: An Alternate Livelihood Option for the Island Community at Lakshadweep". Climate Change and Island and Coastal Vulnerability (Capital Publishing Company) 17: 253–265. doi:10.1007/978-94-007-6016-5_17. 
  20. ^ Shuman, Craig; Gregor Hodgson; Richard F. Ambrose (2005). "Population impacts of collecting sea anemones and anemoneﬁsh for the marine aquarium trade in the Philippines". Coral Reefs 24: 564–573. doi:10.1007/s00338-005-0027-z. 
  21. ^ Watson, Craig; Jeffery Hill (2006). "Design criteria for recirculating, marine ornamental production systems". Aquacultural Engineering 34 (3): 157–162. doi:10.1016/j.aquaeng.2005.07.002. 
  24. ^ Daphne Gail Fautin (1991). "The anemonefish symbiosis: what is known and what is not" (PDF). Symbiosis 10: 23–46. 

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