Amphiprion ocellaris
clown anemonefish
(Also: common clownfish; false clown anemonefish)

Amphiprion ocellaris (Cuvier 1830), the false clownfish, is a tropical marine fish found in parts of Asia and Australia. Its range includes Northwest Australia, Southeast Asia, and as far north as the Ryukyu Islands of Japan (Allen 1997). ()

Amphiprion ocellaris inhabits coral reefs (Allen 1997) and sheltered lagoons up to a depth of 15 meters (Myers 1999). More specifically, it is mainly found in or near the anemones Heteractis magnifica, Stichodactyla gigantean, and Stichodactyla mertensii (Myers 1999) as part of a symbiotic relationship. ()

False clownfish are orange to reddish-brown with three white bands on the head and body. The white bands are outlined in black. Black A. ocellaris, with white bands and black coloring instead of orange, are found off the Northern Territory of Australia (Allen 1997). Amphiprion ocellaris has a rounded caudal fin and may grow up to 110 mm in length (Nelson et al. 1996). There are 11 dorsal spines and 17 pectoral rays that help to distinguish it from the closely related Amphiprion percula. Females are larger than males in this species. ()

Amphiprion ocellaris hatches and enters a short larval stage where it resides close to the surface in a planktonic stage. As they change from larvae to juvenile fish, usually within a day, the fish moves from the surface to the bottom in search of a host anemone (Fautin and Allen 1992). ()

Lifespan has not been studied fully in the wild, but it is believed that A. ocellaris may live 6-10 years (Fautin and Allen 1992). Larval fish are extremely susceptible to predation as they have no way of defending themselves and have high mortality rates. Captivity transfer experiments have been performed to address the possibility of restocking the fish in areas where they have been depleted; these find that survival among transferred fish is higher among smaller A. ocellaris (Nelson et al. 1996). ()

Amphiprion ocellaris exists in a symbiotic relationship with sea anemones, specifically, Heteractis magnifica, Stichodactyla gigantean, and Stichodactyla mertensii (Myers 1999). These fish are dependent upon the anemone for shelter. In open waters these fish are more susceptible to predators and are poor swimmers. In addition, anemones provide protection for the nests (Fautin and Allen 1992). The anemones are observed to generally do better with a host fish and may also benefit possibly from fish consumption of parasites and increased water circulation from fanning (Fautin and Allen 1992). Anemonefishes are protected from the sting of the anemone by their mucus (Fautin and Allen 1992). There is a period of acclimatization that must occur before the fish is immune to the anemone sting. This involves a process in which the fish swims around the anemone rubbing its belly and ventral fins on the ends of the tentacles (MarineBio 1998).

As the juveniles search for an anemone, their survival is contingent upon finding an anemone to reside in, but this process is complicated by the dynamics within the anemone. Because of the hierarchical dynamics within the anemone, the new juvenile fish enters the system at the bottom and is exposed to the worst aggression and may be driven away (Thresher 1984). A. ocellaris are able to find one of the three species of sea anemones by olfactory clues, due to imprinting that occurred while in the nest (Arvedlund and Nielsen 1996). ()

Communication during mating occurs through the male biting, chasing, and extending his fins towards the female (Thresher 1984). The hierarchical system is communicated through aggression by the larger members residing in the anemone at the smaller individuals. Ampiprion ocellaris is able to find host anemones by olfactory imprinting that occurs while in the nest (Arvendlund and Nielsen 1996). ()

Planktonic food such as zooplankton, copepods, and algae are the primary source of food for A. ocellaris (Myers 1999). They are classified as generalized omnivores as they feed on equal amounts of algae and animals (Sano et al. 1984). They are also reported to consume parasites from their host anemones (Thresher 1984). Feeding is also dominated by the hierarchical structure of the group dynamics in the anemone. Because the smaller fish receive the most aggression from the others, they have reduced energy for foraging great distances from the anemone and tend to stay close. Additionally, it is unsafe for the smaller fish to stray farther from the safety of the anemone (Fautin and Allen 1992). The large, dominant fish will forage at greater distances, but generally no farther than several meters from the anemone. ()

Predation on anemonefishes is greatly reduced due to the relationship with the host anemone, whose sting deters potential predators. The eggs are more susceptible to predation, mainly by other damselfishes (Pomacentridae) not including other anemonefishes, and wrasses (Labridae) (Arvedlund et al. 2000). Egg predation susceptibility increases at night as the male is not guarding them and they may fall victim to brittle stars (Ophiotrichidae) (Arvedlund et al. 2000). ()

As mentioned previously (Behavior), A. ocellaris is part of a symbiotic relationship between three species of sea anemones, Heteractis magnifica, Stichodactyla gigantean, and Stichodactyla mertensii (Myers 1999). In this relationship, the fish receives protection from the anemone in the form of daily shelter and for its nest. The anemone receives protection too, as it has been documented that in the absence of a guest fish, the anemones may be attacked by butterfly fish or even turtles (MarineBio 1998). Additionally, in the presence of the fish, bulbs are found on the end of tentacles that are believed to increase surface area available to solar energy (Fautin and Allen 1992). The bulbs are not present in the absence of the fish. ()

None known

Amphiprion ocellaris are part of the tropical fish aquarium trade and certain rare colors of the species are specifically sought (Sadovy and Vincent 2002). They are easily bred in captivity and may be used in research (Thresher 1984). ()

The high demand for the A. ocellaris in the aquarium trade has reduced the population size in some locations, leaving the local populations open to over-exploitation and other threats (Nelson et al. 1996). The species is not classified as threatened or endangered (IUCN 2003); however, as threats to coral reefs increase, A. ocellaris may face habitat degradation and possibly be threatened in the future. Coral reefs face many issues including sedimentation, eutrophication, exploitation of resources, and possible sea temperature increases due to global warming (Bhat 2004). ()