Mates communicate in courtship through movement and touch. During spawning, females swim in a zig-zag pattern over the nest while the male fertilizes the eggs. Males also “shows off” their fins to females, a form of visual communication.
Communication Channels: visual ; tactile
Perception Channels: visual ; tactile ; chemical
Although spinecheek anemonefish are not endangered, there are concerns for populations and their reef habitats due to the "Nemo craze". In the last generation 15 to 30% of the world's reefs have been lost. After release of Disney's "Finding Nemo" movie, which has an anemonefish as its main protagonist, anemonefish sales have increased. Collecting methods are often extremely destructive, permanently damaging reefs.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
The developmental stages of spinecheek anemonefish are egg, larvae, young and adult. The transparent, elliptical eggs are 3-4 mm in size. Anemonefish hatch with advanced alimentary canals and feed on the yolk, which usually lasts for about 3 days. Five days after hatching they develop supranuclear inclusions around the hindgut, which suggests pinocytotic digestion of protein. Between 3 to 5 days after hatching is the period of highest mortality stage for anemonefish if they cannot find food. It is also the time when they transition from endogenous to exogenous feeding. Seven days after hatching they attain gastric glands and by the 9th day they have supranuclear vacuoles that indicate exogenous digestive capabilities. Spinecheek anemonefish hatch 6 to 7 days after fertilization, and then undergo a 7 to 14 day pelagic larval stage. After fertilization, they complete the development of the olfactory organ in 19 days, retinal differentiation in 20 days and skeletal ossification in about 22 days. Spinecheek anemonefish develop more rapidly than other anemonefish species. Their eyes develop especialy rapidly. Vision is directly correlated with the ability to attain food because most larval fish are visual feeders. Olfactory cues are used to detect host anemones. During the larval stage spinecheek anemonefish live on the water surface where they are transported by currents.
Metamorphosis occurs when anemonefish leave surface waters and swim to the sea bottom. It then takes on the color pattern of a juvenile. This process usually takes about one day. This marks the beginning of the settlement period, in which individuals seek out an uninhabited anemone host.
Spinecheek anemonefish, like other anemonefish species, are protandrous hermaphrodites, which means that they change from male to female. Females have gonads that function as ovaries with leftover male testicular tissue. In the case of spinecheek anemonefish, males may be half the size of females and their gonads have dormant ovarian cells as well as functioning testes.
Development - Life Cycle: metamorphosis
There are no known adverse effects of the spinecheek anemonefish on humans.
Spinecheek anemonefish are important to the aquarium suppliers who sell them for profit. These anemonefish, and their relatives, are important ecotourist draws for diving operations. Their symbiotic relationship with Entacmaea quadricolor, helps to protect these anemones.
Positive Impacts: pet trade ; ecotourism ; research and education
Spinecheek anemonefish and their host anemones have a mutualist relationship. Entacmaea quadricolor benefits from having spinecheek anemonefish protect them from butterflyfish (Chaetodontidae), which would otherwise eat their tentacles. Spinecheek anemonefish also clean away debris and parasites from the anemone. Spinecheek anemonefish are protected from most predators through their association with venomous anemones.
Mutualist Species:
Spinecheek anemonefish have a diet rich in copepods and planktonic, larval tunicates. They also eat other kinds of plankton and algae.
Animal Foods: aquatic or marine worms; aquatic crustaceans; other marine invertebrates; zooplankton
Plant Foods: algae; phytoplankton
Primary Diet: carnivore (Eats non-insect arthropods, Eats other marine invertebrates)
Spinecheek anemonefish, Premnas biaculeatus, are found in the Indo-West Pacific, including the coasts of India, Burma, Thailand, Malaysia, Indonesia, Philippines, New Guinea, New Britain, Solomon Islands, Vanuatu and northern Queensland.
Biogeographic Regions: indian ocean (Native ); pacific ocean (Native )
The most important aspect of spinecheek anemonefish habitat is the host anemone. Entacmaea quadricolor, bulb-tentacle sea anemones, are the only host species for spinecheek anemonefish. This anemone species is characterized by polyps 50 to 400 mm in diameter, depending on depth. They have brown tentacles of about 100 mm long with a red tip and white bulb at the end of the tentacle. Spinecheek anemonefish tend to live mainly in solitary specimens of Entacmaea quadricolor on reef slopes. The typical water depth is less than 50 m, because anemones require sunlight to grow. The mutualistic zooxanthellae (living within the anemone) need this sunlight to photosynthesize and provide energy for themselves and the anemone. These anemone prefer tropical warm waters with the temperature ranging between 25 and 28°C (77-82°F).
Range depth: 50 (high) m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: reef ; coastal
The lifespan of spinecheek anemonefish has not been well researched. They live longer in the wild, ranging from 6 to 10 years, and about 3 to 5 years in captivity under good conditions. A related species, Amphiprion perideraion, was recorded living to 18 years.
Typical lifespan
Status: wild: 6 to 10 years.
Typical lifespan
Status: captivity: 3 to 5 years.
Spinecheek anemonefish are among the easiest anemonefish to identify, even when young. They are bright red with 3 bars that are bright white in males and grey in females. Individuals may become bright white if they are provoked. The lines may also be bright yellow.
Range length: <60 to 160 mm.
Average length: 70 mm.
Sexual Dimorphism: female larger; male more colorful
Other Physical Features: bilateral symmetry
The most vulnerable stage for spinecheek anemonefish is during the egg and larval stage, when they are not protected by a host anemone and float freely in the water column. As settled adults, Entacmaea quadricolor protects these symbiotic fish because of their ability to deliver a venomous sting. Wrasses are known to prey on eggs and other fish are likely predators of eggs, larvae, and unsettled juveniles.
Known Predators:
Spinecheek anemonefish have a monogamous mating system and mated pairs may stay together for several years. The dominant female is the largest and has one partner, which is the next largest male within a cluster of anemones. The growth of other anemonefish in the same anemone patch is stunted by the presence of a dominant male and female, keeping them smaller than the dominant male. When one or the other of the dominant individuals dies, subordinates grow and replace the dead individual. For example, if the dominant male dies, the next largest male will replace him and continue to grow to its maximum size.
Males, before spawning, go through an extensive ritual of courtship that consists of displaying the dorsal, anal and pelvic fins. He also chases and nips his mate.
Mating System: monogamous
Spinecheek anemonefish may spawn throughout the year in tropical areas. In cooler water they may spawn during the warm season.
Breeding interval: Breeding may occur throughout the year, depending on water temperature.
Breeding season: In the tropics spawning occurs year-round; those in temperate and subtropical waters spawn when the temperatures are highest in summer and spring.
Range number of offspring: 100 to 1000.
Range gestation period: 6 to 7 days.
Range time to independence: 8 to 12 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sequential hermaphrodite (Protandrous ); sexual ; fertilization (External ); oviparous
Males care primarily for the eggs. Before spawning, males find and prepare a nest for the eggs. He cleans the area by removing the debris and algae from the area. Usually the female ends up joining in the task. During incubation the male guards and cares for the nest. He chases away any possible predators that may want to feast on the eggs, such as wrasses. Male anemonefish use their pectoral fins to fan the eggs and spend time meticulously removing dead eggs and debris from the nest with their mouths. Females will occasionally assist males but mainly spend their time feeding.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male)
Premnas biaculeatus, commonly known as spine-cheeked anemonefish or the maroon clownfish, is a species of anemonefish found in the Indo-Pacific from western Indonesia to Taiwan and the Great Barrier Reef.[2] They can grow up to be about 17 cm (6.7 in).[3] Like all anemonefishes it forms a symbiotic mutualism with sea anemones and is unaffected by the stinging tentacles of the host anemone. It is a sequential hermaphrodite with a strict size-based dominance hierarchy; the female is largest, the breeding male is second largest, and the male nonbreeders get progressively smaller as the hierarchy descends.[4] They exhibit protandry, meaning the breeding male changes to female if the sole breeding female dies, with the largest nonbreeder becoming the breeding male.[5] The fish's natural diet includes algae and zooplankton.[3]
The characteristic that defines this genus is the spine on the cheek. The colors of the body and bars vary according to sex and geographic location. Despite the common name maroon clownfish, only some females have a maroon body color, with a range of color to dark brown. Juveniles and males are bright red-orange. The fish has three body bars which may be white, grey, or yellow. Where the female bars are grey, they can be "switched" rapidly to white if fish is provoked.[5] The size-based dominance hierarchy means in any group of anemonefish, the female is always larger than the male. A significant difference in size is seen in this species, with females being one of the largest anemonefish, growing up to 17 cm (6.7 in) while males are much smaller, usually being 6–7 cm (2.4–2.8 in).[5]
The significant color variations for fish in this species are related to sex and geographic location. Male and juvenile fish are bright red-orange which darkens on the fish changing to female, ranging from maroon to dark brown. The body bars of the female are narrower and the body bars reportedly all but disappear in older females.[6] At least three geographic variations in the color of females are found, with fish from East Timor to Australia retaining white body bars. In the central Malay Archipelago, the head bar tends towards a dull yellow, with the other two body bars being grey. In Sumatra and Andaman Islands, all three body bars are yellow for both male and female, and the female body color can range from a dull maroon to a dark brown. While other species have a blue tinge to their body bars, Amphiprion chrysopterus and A. latezonatus, this geographic variety, is the only anemonefish to have yellow or gold body bars.
Central Malay Archipelago
The female in the Central Malay Archipelago, from North Sulawesi and the Philippines in the north to Komodo Island in the south, has a dull-yellow head bar and grey body bars. Male and juvenile fish are bright red-orange with white bars.
Female from Gilli Lawa Laut, near Komodo Island showing the gold tinged head bar and distinctive cheek spine
Male at Bunaken island, North Sulawesi, showing the bright red-orange colors and three white body bars
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Female at Bunaken island, North Sulawesi, showing the dull-yellow head bar and grey body bars
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The male is significantly smaller than the female, with the female showing the dull-yellow headband, from the Apo Island the Philippines.
East Timor to Australia
In the area from East Timor through New Guinea and Australia, the female has white or grey head and body bars. Male and juvenile fish are bright red-orange with white bars.
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Female at East Timor showing the narrower body bars and maroon color
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Male at East New Britain, PNG showing similar coloration to the male at North Sulawesi
Sumatra
Fish from Sumatra, the Andaman Islands, and Nicobar Islands have yellow body bars on both males and females. This distinctive feature meant they were previously considered a separate species.
Female with striking gold body bars from the Andaman Islands
Female with gold body bars and dark brown body
No similar species are seen because the cheek spine is distinctive of the genus and presently all geographic variations of the fish are considered to be the one species. Genetic analysis has shown that it is closely related to A. percula and A. latezonatus.[7][8]
P. biaculeatus is found in the Malay Archipelago and Western Pacific Ocean north of the Great Barrier Reef.[5]
The relationship between anemonefish and their host sea anemones is not random and instead is highly nested in structure.[9] P. biaculeatus is highly specialised with only one species anemone host, Entacmaea quadricolor bubble-tip anemone,[5] predominantly with the solitary form. The fish chooses the host and one of the primary drivers for host selection is thought to be competition.[10][9] E. quadricolor is highly generalist, hosting at least 14 species, around half of all species of anemonefish.[9] With such competition, P. biaculeatus is considered to be the most territorial of all anemonefish.[10] Competition alone, though, does not explain the preference of P. biaculeatus for the solitary form of E. quadricolor.[11]
P. biaculeatus is currently the only member of the genus Premnas.[3] Historically, anemonefish have been identified by morphological features and color pattern in the field, while in a laboratory, other features such as scalation of the head, tooth shape, and body proportions are used.[5] The spine on the cheek of the fish is the characteristic that distinguishes the genus Premnas from the closely related Amphiprion. P. biaculeatus has been thought to have a monospecific lineage, however genetic analysis has shown that it is closely related to A. percula and A. latezonatus.[7][8]
Genetic analysis suggests P. biaculeatus is monophyletic with Amphiprion, closely related to A. ocellaris and A. percula.[12] This would make Premnas a synonym of Amphiprion.[13]
The taxon epigrammata from Sumatra probably should be recognized as a distinct species, Premnas epigrammata (Fowler, 1904).[14] The recent precedents of the recognition of A. barberi as a distinct species from A. melanopus and A. pacificus being distinguished from A. akallopisos demonstrate the need to show not only geographic and morphological differences, but also genetic data to confirm the separation of the proposed species.[15][16]
In 2021 an expansive phylogenetic analysis of the damselfishes[17] has reclassified the Maroon Clownfish from the monotypic genus Premnas to a junior synonym of Amphiprion. The species name remains unchanged, thus the Maroon Clownfish is now Amphiprion biaculeatus. Reef fish taxonomist Yi-Kai Tea agrees, based on DNA studies, "Premnas has been refuted for ages."[18]
The fish has successfully bred in a home aquarium.[3] Being one of the larger anemonefish and the most aggressive, these characteristics need to be accommodated in any aquarium setup.[19]
P. biaculeatus has been subject to selective breeding in captivity. One of the more prominent traits is the "lightning" morph which is characterized by broken, jagged white body bars that have a honeycomb appearance.[20] One of the first times this trait was observed was in a wild-caught pair from Fisherman's Island near Port Moresby, Papua New Guinea.[21]
The maroon clownfish has been successfully crossbred with A. ocellaris to create the hybrid named the "blood orange clownfish" by the Florida aquaculture company, Oceans, Reefs and Aquariums.[22] The body of this hybrid more closely resembles A. ocellaris, but possesses a darker orange hue, grows larger, and has a more fiery temperament, features characteristic of its P. biaculeatus genes.[22]
Maroon clownfish
Maroon clownfish and a tang
Premnas biaculeatus, commonly known as spine-cheeked anemonefish or the maroon clownfish, is a species of anemonefish found in the Indo-Pacific from western Indonesia to Taiwan and the Great Barrier Reef. They can grow up to be about 17 cm (6.7 in). Like all anemonefishes it forms a symbiotic mutualism with sea anemones and is unaffected by the stinging tentacles of the host anemone. It is a sequential hermaphrodite with a strict size-based dominance hierarchy; the female is largest, the breeding male is second largest, and the male nonbreeders get progressively smaller as the hierarchy descends. They exhibit protandry, meaning the breeding male changes to female if the sole breeding female dies, with the largest nonbreeder becoming the breeding male. The fish's natural diet includes algae and zooplankton.
