Clark’s Anemonefish is a small-sized fish that grows up to 10 cm as a male and 15 cm as a female. It is stocky, laterally compressed, and oval to rounded.
It is colourful, with vivid black, white, and yellow stripes, though the exact pattern shows considerable geographical variation. Usually, it is black dorsally and orange-yellow ventrally, the black areas becoming wider with age. There are two vertical white bands, one behind the eye and one above the anus, and the caudal peduncle is white. The snout is orange or pinkish. The dorsal and caudal fins are orange-yellow, and the caudal fin is generally lighter in tone than the rest of the body, sometimes becoming whitish.
Clark’s Anemonefish is the most widely distributed anemonefish, being found in tropical waters from the Indian Ocean to the Western Pacific.
Clownfish or Anemonefish are fishes that, in the wild, form symbiotic mutualisms with sea anemones and are unaffected by the stinging tentacles of the host anemone. 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. Clownfish are small-sized, 10 – 18 centimetres, and depending on species, they are overall yellow-orange or reddish or blackish colour, and many show white bars or patches. Within species, there may be colour variations, most commonly according to distribution, but also based on sex, age and host anemone. Clownfish are found in warmer waters of the Indian and Pacific oceans and the Red Sea in sheltered reefs or in shallow lagoons.
In a group of Clownfish, there is a strict dominance hierarchy. The largest and most aggressive fish is female and 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. They are not aggressive.