The tomato clownfish (Amphiprion frenatus) is a species of marine fish in the family Pomacentridae, the clownfishes and damselfishes. It is native to the waters of the Western Pacific, from the Japan to Indonesia. Other common names include blackback anemonefish, bridled anemonefish, fire clown, and red tomato clown. Characteristics of anemonefish 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, see . 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, , and depending on species, they are overall yellow, orange, or a reddish or blackish color, and many show white bars or patches. Within species there may be color 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. Description The adult fish is bright orange-red, with a white head bar or vertical stripe just behind the eyes, joined over the head and with a distinctive black outline. Females are mainly blackish on the sides. Males are considerably smaller and are red overall. Juveniles are a darker red, with two or three white bars. They have 9-10 dorsal spines, 2 anal spines, 16-18 dorsal soft rays and 13-15 anal soft rays. They reach a maximum length of . Color variations The only color variation is sex related with females having darker coloration or dark spots on their sides. Similar species The Australian clownfish (A. rubrocinctus) has a similar coloration, however the female does not have the distinctive black outline of the white band, the band is poorly developed and may be discontinuous on top of the head. Geographic location is the easiest way to distinguish small juveniles as they are otherwise difficult to distinguish.