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Amphiprion frenatusBlackback anemonefish(Also: Fire clown; Onebar anemonefish; Red clown; Tomato clownfish)

By Kristen Leutheuser

Geographic Range

Tomato clownfish are known to be found in the Oriental Region of the Western Pacific, namely, South China Sea, Indonesia, Singapore, Malaysia, Thailand, Viet Nam, China, Philippines, and Taiwan. They have been found to inhabit waters as far north as the Ryukyu Islands and the southern parts of Japan. The longitudinal coordinates for this area are 25 N - 35 S. (Fautin and Allen, 1992)

Habitat

Tomato clownfish are known to inhabit lagoon reefs, particularly with embayments. According to Fautin and Allen (1992), this species does not migrate, and has developed a relationship with the anemone Entacmaea quadricolor. (Fautin and Allen, 1992)

  • Aquatic Biomes
  • reef
  • Range depth
    1 to 12 m
    3.28 to 39.37 ft

Physical Description

Tomato clownfish have a distinct orange body, which may turn black in older individuals. Behind the head of the fish, a black-edged bar extends from the top of the head towards the belly. A second black-edged white bar may be found around the mid-section of the body.

Amphiprion frenatus have 9-10 dorsal-fin spines and 16-18 dorsal soft rays. This species also has 2 anal-fin spines and 13-15 anal soft rays.

Tomato clownfish can grow up to 14 cm in length. Females are larger than males. (Fautin and Allen, 1992)

  • Sexual Dimorphism
  • female larger
  • Range length
    14 (high) cm
    5.51 (high) in

Development

Beginning as an egg, tomato clownfish will take about one week to hatch and become larvae. After hatching, larvae will drift for about 16 days in plankton-rich waters. At the end of this drifting journey, the larvae will look for anemones of their own to inhabit. Their development from there depends upon social roles. A juvenile will only develop into a sexually mature male if this role in the anemone is not already filled. When the female of the anemone is absent, the largest mature male will then change into the sexually mature female. (Myers, 1999)

Damselfishes that live in anemones have biological attributes that help them to live in this unique environment. As they mature, they gain a special mucus coat that has specific chemicals that counter the anemone's sting. These fishes are also known to have a special swimming pattern that helps them to survive in the anemone. (Allen, 1997)

According to Wickler (1963), Amphiprion frenatus, like other anemonefishes, is not immune to the anemone, but instead stimulates the nematocysts (stinging cells) to fire. If these fish choose to live outside of an anemone, they usually take up residence in coral branches.

It is possible to make a general guess at the age of tomato clownfish by the stripes on their bodies. When young, these fish will have more white stripes on their hind regions. However, not all individuals lose the juvenile pattern as they mature. (Wickler, 1963)

Reproduction

A pair of tomato clownfish will mate for life. However, if one partner leaves, then the other will find a replacement for its lost mate. (Wickler, 1963)

One of the most interesting characteristics of anemonefishes is that all offspring are born male, and mature as such. Therefore, all females are sex-reversed. This sexual metamorphosis occurs when the female of a group leaves. This will trigger the largest male remaining to switch sexes and will allow the largest juvenile to become a mature male. The adult pair will then continue to stunt the growth of the remaining offspring.

When courting a female, a male will exhibit both sterotyped and ritualised behavior. A male will chase a female, as he becomes more bold. He also has the tendancy to show off for his mate by erecting his dorsal, anal, and pelvic fins as he remains in one spot near her, much like a statue. Another form of behavior recorded among A. frenatus is "signal jumping," which means that a male will move rapidly around an anemone in an up and down manner. In the beginning of their courtship, a male will also spend a large amount of time picking out the nesting site that he will eventually guard if he is successful in mating with a female. At the end of courtship, she will also help her mate in clearing the nesting site of algae and other debris. When laying eggs, a female will place the adhesive eggs on a rock near the anemone. The male then watches over them until they hatch.

Tomato clownfish, like all Amphiprion, will breed all year long in the tropics, but only in the warmer months of temperate locations. Spawning occurs during a full moon, which is characteristic of all anemomefishes. (Fautin and Allen, 1992; Myers, 1999)

  • Breeding interval
    Tomato clownfish, like all Amphiprion, will breed all year long in the tropics, but only in the warmer months of temperate locations.
  • Breeding season
    Spawning occurs during a full moon, which is characteristic of all anemome fishes.
  • Range number of offspring
    100 to >1,000
  • Average time to hatching
    6-7 days
  • Average time to independence
    8-12 days

After the eggs are laid near the host anemone, the male looks after the eggs, and both the male and female will protect the eggs as well. After the larvae hatch, they swim away to find an anemone of their own to inhabit, and no further care is given by the parents. (Myers, 1999; Wickler, 1963)

  • Parental Investment
  • pre-hatching/birth
    • protecting
      • male
      • female

Lifespan/Longevity

The knowledge surrounding longetivity for this species is sparse, even though more is known about this species than other anemonefishes. At most, they live 6-10 years in teh wild, and 18 years in captivity. (Fautin and Allen, 1992)

  • Average lifespan
    Status: wild
    6-10 years
  • Range lifespan
    Status: captivity
    18 (high) years

Behavior

Tomato clownfish, like many other anemonefishes, have a complex social hierarchy that rules not only who is in charge of the host anemone, but also the size of the other fish that live within it. At the bottom of the hierarchy are the juvenilles. Usually several juveniles will share one anemone with a mating pair. A sexually mature male is next in line in the hierarchy, with the female at the top. All A. frenatus are born as males, and will only change into a female when the female of the host anemone has left.

One cannot tell the age of a tomato clownfish by simply measuring its size. The female initiates a non-threatening, harassing behavior towards the mature male with whom she shares the anemone. From this behavior, the male in turn harasses the juveniles in the same manner. Since the juveniles are constantly being chased by the male and sometimes the female, they seldom have time to eat enough nutrients to grow any larger. This behavior inhibits the growth of the newer fish to the anemone. Even the male is half as large as the female due to her consistant harassment of him. Therefore, when the female is absent from the anemone, both the male and the juveniles experience a large growth spurt. (Fautin and Allen, 1992)

Home Range

The territory size of the anemonefishes depends upon the size of the fish. The smallest tomato clownfish will usually stay very close to the host anemone when foraging for food due to their increased risk of predation. Larger anemonefishes that are at the top of the social heirarchy in the host anemone will travel many meters from their host. (Fautin and Allen, 1992)

Communication and Perception

Not much is known about the communication of tomato clownfish, except that when they are either defending themselves or attacking others, they will make a "tack-tack" sound. (Wickler, 1963)

Food Habits

Tomato clownfish eat algae, zooplankton, and small, aquatic crustaceans.

A characteristic of all anemonefish belonging to the genus Amphiprion is that they are mutualistic with anemones. This means that they live together with large anemones, and each helps the other species. When a tomato clownfish brings food back to an anemone, the anemone is rewarded with crumbs from the meal. In turn, the fish is protected from predators while within the anemone. The anemonefish also help the anemones by cleaning and caring for them, which again benefits the anemone greatly. (Allen, 1997)

  • Plant Foods
  • algae

Predation

In all of the literature available, no specific predators were given for the tomato clownfish or even for their genus, Amphiprion.

Ecosystem Roles

Amphiprion frenatus is a symbiont to the bulb-tentacle sea anemone, Entacmaea quadricolor. Although they can both live without each other, their health and rate of survival are increased when tomato clownfish live within its tentacles. (Fautin and Allen, 1992; Fautin and Allen, 1992)

Mutualist Species
  • Entacmaea quadricolor, bulb-tentacle sea anemones

Economic Importance for Humans: Positive

Tomato clownfish have a positive economic importance for humans through the pet trade industry.

Economic Importance for Humans: Negative

No literature found stated that tomato clownfish have a negative economic importance for humans.

Conservation Status

This species is not listed on any of the endangered or threatened lists that are listed below.

Contributors

Kristen Leutheuser (author), University of Michigan-Ann Arbor, William Fink (editor, instructor), University of Michigan-Ann Arbor, Matthew Wund (editor), University of Michigan-Ann Arbor.

Glossary

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

herbivore

An animal that eats mainly plants or parts of plants.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

planktivore

an animal that mainly eats plankton

protandrous

condition of hermaphroditic animals (and plants) in which the male organs and their products appear before the female organs and their products

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

References

Allen, G. 1997. Marine Fishes of Tropical Australia and South-East Asia. Perth, Western Australia: Western Australian Museum.

Fautin, D., G. Allen. 1992. Field Guide to Anemone Fishes and Their Host Sea Anemones. Perth: Western Australian Museum. Accessed October 29, 2004 at http://biodiversity.uno.edu/ebooks/intro.html.

Myers, R. 1999. Micronesian Reef Fishes: A Field Guide for Divers and Aquarists. Territory of Guam: Coral Graphics.

Wickler, W. 1963. The Marine Aquarium. Stuttgart: T.F.H. Publications, Inc Ltd..

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