Melanotaenia misoolensis (Gam River, Misool Island) - photo© Gerald Allen

Melanotaenia misoolensis

Allen, 1982
Misool Rainbowfish

Species Summary
Melanotaenia misoolensis was described from 23 specimens collected from Misool Island off the western extremity of New Guinea. Adult males are bluish with a bronze or golden sheen, and silvery white on the lower half. The upper back and sides often reflect bronze or golden sheen and there is a series of narrow oranges lines on the sides between each horizontal row of scales. There is also a diffused midlateral band extending from the upper corner of the opercula margin to the middle of the caudal fin base, often consisting of blotches. The fins are translucent to light yellow. Males grow to a length of around 6 cm and are usually deeper bodied than females.

They are closely related to Melanotaenia catherinae which is endemic to Waigeo Island, a large island lying approximately 160 km north of Misool. Both species are similar in colour; however, the mid-lateral stripe of M. catherinae is significantly wider, having a maximum width of about three scales compared with 1½ scales for M. misoolensis. Moreover, the midlateral stripe of M. misoolensis is nearly covered entirely by the pectoral fin, whereas it is broadly exposed (at least one scale row) above the pectoral fin of M. catherinae. In addition, the latter species lacks the dusky spot on the fin membrane behind the last dorsal spine and has a dusky soft dorsal fin which is often blackish in adult males. M. misoolensis, in contrast, has a dusky spot behind the last dorsal spine and the soft dorsal fin is yellowish-orange. The only meristic difference noted is related to counts for the soft anal rays. M. misoolensis usually has 22 to 25 rays (one specimen with 20 rays) compared with 19 to 21 rays for M. catherinae.

Melanotaenia misoolensis - photo© Christophe Mailliet

Distribution & Habitat
Melanotaenia misoolensis is currently only known from Misool Island. They have been found in moderately fast-flowing clear-water streams running through primary rainforest. Misool Island is one of the four major islands in the Raja Ampat Islands. Misool is a relatively large (approximately 90 x 38 km) island lying just to the south of the western extremity of New Guinea and separated from the mainland by a distance of 32 kilometres. The island has an area of about 2034 km² with a maximum elevation of 990 m. M. misoolensis have been found in moderately fast-flowing clear-water streams running through primary rainforest. Other rainbowfishes have been collected from several other islands in the Raja Ampat group of islands: M. batanta (Batanta Island); M. catherinae (Batanta and Waigeo Islands); M. fredericki and M. salawati (Salawati Island) and M. synergos (Batanta Island).

In October 1948, a Dutchman by the name of Maurits Anne Lieftinck collected some rainbowfishes from a tributary of the Wai Tama River near Fakal Village on Misool Island. However, the collection remained unstudied in the Zoological Museum of the University of Amsterdam in the Netherlands until officially described by Gerald R. Allen in 1982. The species was named Melanotaenia misoolensis in reference to the type locality. Live specimens were collected for the aquarium hobby by Heiko Bleher in 2001.

Allen G.R. (1982) A new species of freshwater rainbowfish (Melanotaeniidae) from Misool Island, Indonesia. Records of the Western Australian Museum. 10(2): 105-109.

Allen G.R. (1991) Field guide to the freshwater fishes of New Guinea. Christensen Research Institute, Madang, Papua New Guinea.

Adrian R. Tappin
Updated December, 2008

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Melanotaenia misoolensis