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| Melanotaenia oktediensis - photo© Neil Armstrong |
Allen and Cross, 1980
Oktedi Rainbowfish
Description
Body colouration is coppery brown above a prominent mid-lateral line and pale mauve to white below. Initially collected by C. Boyden in the Ok Tedi River at Tabubil, Papua New Guinea in 1974. In 1975, Tyson Roberts collected them from the lower portion of Karamonge Creek, a tributary of the Ok Tedi River during an ichthyological survey of the Fly River. In 1978 he published the results of his Fly River study and mistakenly identified the single female rainbow as Melanotaenia vanheurni, a species found in the Mamberamo basin, northern New Guinea. After examining specimens in the Zoologisch Museum, Amsterdam and the American Museum of Natural History, New York, Allen and Cross recognised them as a distinct species and named them Melanotaenia oktediensis after the Ok Tedi River. Both species have a relatively elongated body shape, a prominent mid-lateral band, and are characterised by relatively numerous soft dorsal and anal fin rays. The most significant difference is the position and length of the mid-lateral band.
Distribution
Tributaries of the Ok Tedi River which is one of the main headwater streams of the Upper Fly River system. Rather uncommon in the main river, which is mostly populated by Melanotaenia splendida rubrostriata.
Habitat & Ecology
The tributaries of the Ok Tedi River are cool, clear, relatively fast flowing rainforest streams with rocky bottoms. Water conditions reported from this habitat are temperature 17-24° Celsius, pH 7.3-8.7, hardness 20 to 80 ppm and a high dissolved oxygen content of 6.9 - 10.0 mg/l. Melanotaenia oktediensis may reach a maximum size of 12 cm, but usually less than 10 cm. Spawning females produce between 100 and 200 eggs. Eggs adhere to water plants and hatching occurs around 9 to 12 days at temperatures between 24 to 28° Celsius.
Remarks
Gerald Allen collected live specimens in 1982 and they were introduced to the Australian hobby. In 1983 they were sent to Europe and Northern America, but they have never been readily available.
© Copyright Adrian R. Tappin
Updated January, 2007.
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