Clownfish, or Anemonefish, made famous by the movie “Finding Nemo”, can be found frequently in the waters of the Andaman Sea. Anemonefish are one of three subfamilies of the Damselfishes (Pomacentridae), which include Chromininae (the pullers), Pomacentrinae (the demoiselles) and Amphiprioninae (the anemonefish). In tropical areas, an estimated 300 species of Damselfishes occur, making them one of the most numerous fishes in coral reef habitats. Anemonefish are the smallest subfamily of damselfishes, contributing 28 different species, five of which are found in the waters off Thailand and Burma. These include the Western or False Clownfish (Amphiprion ocellaris), the Skunk Anemonefish (A. akallopisos), the Saddleback or Tomato Anemonefish (A. ephippium), Clarke’s Anemonefish (A. clarkii) and the Northern Indian Anemonefish (A. Sebae).

All anemonefish, no matter which species, will develop a symbiotic relationship with a certain anemone–usually for life. Depending on whether the anemonefish is a specialist or a generalist will determine which type of anemone it will seek out. A specialist will choose only one species of anemone to be its host, whereas a generalist–being less specific–could choose from a number of different hosts. Before these fish are born, they are imprinted with the type or types of anemone they must find in order to establish a successful symbiotic relationship. As feti, anemonefish are imprinted with olfactory cues from their mothers, thus they use their sense of smell in order to find the host anemone.

Once a juvenile anemonefish has found its new home, it must acclimatize to the anemone’s nematocysts or stinging cells. It does this by swimming slowly around the anemone’s tentacles while building up a mucous layer over its scales. The anemonefish is then able to live in the protection of the anemone’s stinging tentacles without injuring itself, while providing protection for the anemone by eating certain prey of their anemone host, such as polycheate worms. The symbiotic relationship observed between anemones and their anemonefish is one of mutualism, meaning that both species benefit from the relationship.

The lifecycle of an anemonefish is quite different from that of other reef fishes (such as parrotfish or wrasse). Anemonefish are termed “sequential hermaphrodites” as they are born males, and eventually, if they become the largest fish in the anemone, they morph into a female. When this female dies, the next ranking male becomes the new matriarch. Anemonefish live only to three or four years of age, therefore most of their days are spent as males.

An anemonefish’s diet consists mostly of zooplankton, algae and copepods, and as a female they can grow to be about 10cm in length. A female will lay numerous clutches of demersal eggs, meaning they are laid in patches on hard substrate–usually underneath a cluster of stinging tentacles. When these eggs hatch, the baby anemonefish must find their way to their anemone host using the olfactory cues passed to them. The ratio of juveniles that survive is low, but those that make it have a good chance of living out full lives in their new home.

While working as a full time Divemaster in Hawaii, Anik Clemens also worked part-time at a Microbiology Lab affiliated with the University of Hawaii. She can be contacted at anikclemens@yahoo.com.