Animal Diversity Web

Geographic Range

Wild Melanotaenia boesemani, or Boeseman’s Rainbowfish, is indigenous to the Ajamaru Lakes region and Aitinjo Lake located in Vogelkop Peninsula of West Papua (Allen & Boeseman, 1982). According to Gerald Allen’s book, Rainbowfishes: Their identification, care and breeding, Boeseman’s Rainbowfish was recorded commonly in small creeks leading into Ajamaru Lake. Species of the family, Melanotaeniidae, have been found to inhabit freshwater streams, lakes, and swamp in Northern Australia to New Guinea (Allen, 1980). Melanotaeniidae have also been recorded to reside in river drainage of Australia (Shelly, 2004). Rainbowfish has the ability to populate in various habitats and a high percentage to become endemic in that habitat (Kadarusman et al., 2010). However, captive bred Boeseman’s Rainbowfish have been found to be raised in limited farms as aquaculture products in Indonesia since 1983 (Nugraha et al., 2015). Melanotaeniidae was recorded to only be absent in northeastern New Guinea and elevations of over 1000 meter and below 2000 meter (Unmack et al., 2013).

• Biogeographic Regions
• australian
  • native

• Other Geographic Terms
• island endemic

Habitat

Wild Melanotaenia boesemani mainly inhabits Ajamaru Lakes and nearby tributaries as well as Aitinjo Lake (Allen, 1995). The Ajamaru lake has been recorded as relatively clear water with numerous aquatic vegetation and alkalinity pH recording of 8.0 (Allen, 1995). Maximum depth of Ajamaru Lake is 10 meter and 55m above sea level (Allen, 1995). Hobby Aquarists keeps the species in similar water parameters of 7.0 to 8.0 in pH and temperature ranging from 25-28 degree Celsius (Allen, 1995).

• Habitat Regions
• freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Other Habitat Features
• estuarine

• Range elevation

  55 above sea level (high) m

  ft

• Range depth

  10 (low) m

  32.81 (low) ft

Physical Description

The Boeseman’s Rainbowfish share several similar physical characteristics with other rainbowfishes in the family, Melanotaeniidae, such as: oblong to slender shape, upper part of snout and interorbital region flattened, and eye is relatively large (Allen, 1980). Melanotaeniidae possess a unique V-shaped enclosure between the pelvic rays and abdomen which contain the uro-genital opening (Allen, 1980). Another unique character that pertains to the Melanotaeniidae is a distinct sexual dimorphism compare to the other families in the order, Athriniformes, that has little to no sexual dimorphism (Allen, 1980). Melanotaenia boesemani contains the following meristic: dorsal rays IV to VI, 10 to 14; anal rays I, 17 to 23; and 13-16 pectoral rays (Allen & Cross, 1980). A special physical characteristics wild Boeseman’s Rainbowfish possesses is the head and frontal part of the body has a blue-grey coloration while the rear is bright orange (Allen, 1995). Including its vibrant colors scheme, Boeseman’s Rainbowfish has 2-3 slender bars between the color zones (Allen, 1995). The dorsal fins of the species are typically orange with white borders (Allen, 1980). Female of the species are typically being not as vibrant in color as the males (Allen, 1995). Compare to other species in the family, Boeseman’s Rainbowfish tends to have tall body scales (Allen & Cross, 1980).

• Other Physical Features
• bilateral symmetry

• Sexual Dimorphism
• male more colorful

Development

Compare to adult Boeseman’s Rainbowfish, younglings and fry are dependent on vegetation for protection from predators until maturity (Allen, 1995). Melanotaenia boesemani usually stop growing after 11.5 cm in length (Allen, 1995). As male Boeseman’s Rainbowfish become sexually active, they began to flash a white coloration on their head (Allen, 1995).

Reproduction

There is little available information on reproduction in Melanotaenia boesemani mating system.

According to Allen and Cross original description, Boeseman’s Rainbowfish have been successful at breeding in captivity. Breeding of Melanotaeniidae typically spawn in the early morning (Allen, 1995). Rainbowfish will typically breed in pair or in group, and males will begin to flash colors on the top of their head (Allen, 1995). Female Boeseman’s Rainbowfishes will typically lay 10-20 eggs, and take about 2 weeks to hatch (Allen, 1995). Datum has shown that peak oocyte maturation and spawning season occurs in August for Boeseman’s Rainbowfish (Hismayasari et al., 2015).

• Key Reproductive Features
• sexual
• oviparous

• Breeding season

  Spawn early morning

• Range number of offspring

  10 to 20

• Average time to hatching

  2 weeks minutes

There is little available information on Melanotaenia boesemani parental investment.

Lifespan/Longevity

Melanotaeniidae naturally began as 4mm fry in length and survive on yolk reserves (Allen, 1995). Very little detail is known about the wild Boeseman’s Rainbowfish lifespan in their natural habitat.

Behavior

Melanotaeniidae tends to stay in schooling groups and resides near the surface of the water to feed (Allen, 1995). Males Boeseman’s Rainbowfish during breeding season will become aggressive while flashing colors on top of their heads (Allen, 1995). Fry and young rainbowfish will tend to stay in vegetation cover in large numbers to escape from predators and as well as from adult rainbowfish (Allen, 1995).

• Key Behaviors
• natatorial
• motile
• colonial

Communication and Perception

There is little available information on communication and perception in Melanotaenia boesemani.

• Perception Channels
• tactile
• chemical

Food Habits

Boeseman’s Rainbow fish are considered omnivores (Shelly, 2004). According to Allen and Cross original description, the gut content shows a diet of small insects and bits of algae and crustaceans. Boesman’s Rainbowfish have been said to have a strong formic taste to them due to their diet of insects which includes ants (Shelly 2004).

• Primary Diet
• carnivore
  • insectivore
  • eats non-insect arthropods
• omnivore

Predation

Very little is known about the Boeseman’s Rainbowfish Predators, but Melanotaeniidae are usually preyed on by larger fishes including freshwater snappers, grunters, and cardinal fishes (Allen, 1995). Adults Rainbowfishes have been recorded to prey on fry and younger rainbowfishes in both nature and captivity. Rainbowfishes are also known to be eaten by various species of water fowls specifically during water droughts (Allen, 1995). According to Allen and Cross1980, the Melanotaeniidae have known to be eaten by small villages in Papua and West Papua.

Ecosystem Roles

Melanotaeniidae plays an in central role in fish communities of various water habitats by populating in areas such as rivers, lakes, and reservoirs (Allen, 1995).

Economic Importance for Humans: Positive

In 1980s, wild Boeseman’s Rainbowfish were caught and exports by the tens of thousands (Shelly, 2004). In 1989, an approximate sixty thousand Boeseman’s Rainbowfish were caught and exported every month for exporters (Allen, 1995). Today’s species are mostly captive bred due to the fact that the wild has been place under the critically endangered list (Nugraha et al., 2015).

• Positive Impacts
• pet trade

Economic Importance for Humans: Negative

Very little is known if Melanotaenia boesemani have any adverse affect on humans if any.

Conservation Status

Wild Melanotaenia boesemani are considered critically endangered and place in the International Union for Conservation of Nature or IUCN Red List (Nugraha et al., 2015). The major factor to the species reaching endangerment was the interest in the them by hobbyist. (Allen, 1995). In 2014, microsatellite DNA markers were place on Boeseman’s rainbowfish to keep track of their population growth (Nugraha et al., 2014). Research recorded from Nugraha and her colleagues in 2015 included farmers claiming that captive bred Boeseman’s Rainbowfish has shown discoloration, growth rate is slower, rising abnormalities compare to their wild counterparts.

• IUCN Red List

  Critically Endangered

Contributors

John Le (author), Louisiana State University, Prosanta Chakrabarty (editor), Louisiana State University.

References

Allen, G. 1995. Rainbowfishes: their identification, care, and breeding. Blacksburg, VA: Tetra.

Allen, G. 1980. A Generic Classification of the Rainbowfishes (Family Melanotaeniidae). Records of the Western Australian Museum, 8(3): 449-490.

Allen, G., M. Boeseman. 1982. A Collection of F'reshwater fishes from Western New Guinea with Descriptions of Two New Species (Gobiidae and Eleotridae). Records of the Western Australian Museum, 10(2): 67-103.

Allen, G., N. Cross. 1980. DESCRIPTIONS OF FIVE NEW RAINBOWFISHES (MELANOTAENIIDAE) FROM NEW GUINEA. Records of the Western Australian Museum, 8: 377-396.

Hismayasari, I., A. Marhendra, S. Rahayu, D. Supriyadi. 2015. Gonadosomatic index (GSI), Hepatosomatic index (HSI) and proportion of oocytes stadia as an indicator of rainbowfish Melanotaenia boesemani spawning season. International Journal of Fisheries and Aquatic Studies, 2(5): 359-362.

Kadarusman, S., E. Paradis, L. Pouyard. 2010. Description of Melanotaenia fasinensis, a new species of rainbowfish(Melanotaeniidae) from West Papua, Indonesia with comments on the rediscovery of M. ajamaruensis and the endangered status of M. parva.. Cybium: international journal of ichthyology, 34(2): 207-215.

Nugraha, M., L. Pouyaud, O. Carman, U. Widyastuti, J. Avarre. 2014. Development of twelve novel polymorphic microsatellite DNA markers for the Boeseman’s rainbowfish (Melanotaenia boesemani) and tests for their cross-utility in 21 rainbowfish species from West Papua (Indonesia). European Journal of Wildlife Research, 60(6): 941-946.

Nugraha, M., L. Pouyaud, O. Carman, U. Widyastuti, M. Junior, J. Avarre. 2015. Genetic Diversity of Boesemans Rainbowfish (Melanotaenia Boesemani) Reared in Indonesian Farms Compared to Endangered Natural Populations. Tropical Conservation Science, 8(3): 795-812.

Shelly, R. 2004. Atheriniformes (Rainbowfishes and Silversides). Grzimek's Animal Life Encyclopedia, 5: 67-77.

Unmack, P., G. Allen, J. Johnson. 2013. Phylogeny and biogeography of rainbowfishes (Melanotaeniidae) from Australia and New Guinea. Molecular Phylogenetics & Evolution, 67(1): 15-27.