Clownfish
The symbiotic reef dweller with a size-based hierarchy and sex-changing ability.
Clownfish or anemonefishes (genus Amphiprion) are saltwater fish found in the warm and tropical waters of the Indo-Pacific. They mainly inhabit coral reefs and have a distinctive colouration typically consisting of white vertical bars on a red, orange, yellow, brown or black background. Clownfish developed a symbiotic and mutually beneficial relationship with sea anemones, on which they rely for shelter and protection from predators. In turn, clownfish protect the anemone from anemone-eating fish, as well as clean and fan them, and attract beneficial microorganisms with their waste.
Quick Facts
- Scientific name:
- Amphiprioninae (subfamily)
- Habitat:
- Indo-Pacific coral reefs
- Diet:
- Omnivore (algae, zooplankton, small crustaceans)
- Lifespan:
- 6 to 10 years in the wild
- Conservation status:
- Least Concern
Lore & Background
Clownfish are damselfishes (family Pomacentridae) in the genus Amphiprion. The genus was coined by Marcus Elieser Bloch and Johann Gottlob Theaenus Schneider in 1801. Georges Cuvier considered the maroon clownfish morphologically different enough to be placed in its own genus Premnas in 1816, but in 2021 phylogenetic analyses found the species to be within Amphiprion, making Premnas a junior synonym. In 1975, ichthyologist Gerald R. Allen placed clownfish in their own subfamily Amphiprioninae.
A 2009 genetic study suggested creating the tribe Amphiprionini and moving them to the subfamily Pomacentrinae. Eschmeyer's Catalog of Fishes considers the genus to be part of Pomacentrinae though scientific papers still use Amphiprioninae. The clownfish lineage diverged from other damselfishes around 35 million years ago during the late Eocene, and the most recent common ancestor of extant species is dated around 10.5 mya during the Early Miocene.
A 2014 study placed their origin in the waters of the Malay Archipelago. Prior to 2025, 28 living species were recognised along with two hybrids; in 2025, a new species, the Polynesian anemonefish (A. maohiensis), was classified.
Reader's Guide
Clownfish live in groups consisting of a breeding female and male, along with some non-breeding individuals. They have a size-based dominance hierarchy with the breeding female ranking at the top, followed by the breeding male and then the largest non-breeder and so on. When the female disappears, the breeding male changes sex and takes her place while the others move up the hierarchy. During reproduction, the female deposits eggs on a rock near their anemone, and the male fertilises them. After hatching, clownfish disperse into the open ocean as larvae, eventually settling on the bottom and searching for an anemone host as juveniles. Clownfish are omnivorous and mostly feed on plankton. They are limited by the distribution of their sea anemone hosts, which is usually near the surface.
Did You Know?
- Clownfish have saw-shaped edges along the operculum and under the eyes, which is the source of their genus name Amphiprion (Greek for 'on both sides' and 'saw').
- The maroon clownfish can reach 17 cm long while the orange clownfish reaches only 11 cm.
- Clownfish can see both in colour and ultraviolet light.
- The ocellaris clownfish ranks among the most commonly traded marine fish.
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