Melanotaenia irianjaya (Hoa Creek) - photo© Gerald Allen

Melanotaenia irianjaya

Species Summary
Male specimens of Melanotaenia irianjaya have a bluish-grey or slightly violet colour on the upper half of the body while the lower half of the body is silvery-white with a slight yellowish-orange hue posteriorly. There is a broad, bluish midlateral band, which is most prominent on the rear-half of the body. The dorsal and anal fins are reddish with narrow white margins. Mature males develop a very large and elongated anal fin. The caudal fin is reddish and has distinctive black upper and lower margins. The pelvic and pectoral fins are mainly transparent. This species is unusual in having the middle rays of the dorsal and anal fins longer than the other rays. Instead the middle rays of these fins are the longest, a feature shared only by Melanotaenia corona from north-central New Guinea. Unlike most rainbowfishes, males of this species lack the pronounced elongation of the posterior dorsal and anal fin rays. Males are more brightly coloured, larger, and deeper bodied than females. Males may reach a maximum size of 12 cm, but females are usually less than 10 cm.

Distribution & Habitat
Melanotaenia irianjaya are found primarily in river systems that drain into Bintuni Bay, in the southern Vogelkop Peninsular region. In November 1982, Gerald Allen and Heiko Bleher collected M. irianjaya from streams at Fruata Village (2°59'S, 132°32'E) and Merdai Village (1°35'S, 133°20'E). In 2008 they were collected from Padang Creek (2°34.691'S, 133°08.973'E), located approximately 40 km north-west from Fruata Village. Then in 2010 they were collected from Wat Creek (2°58.576'S, 133°27.971'E), near the village of Fruata.

Habitats consist of rainforest streams ranging from slightly turbid and slow flowing over flat terrain to clear, moderately fast flowing through hills. The habitat generally consists of moderate flowing, clear rivers and creeks with pH and temperatures ranging between 7.3-8.5, and 24-29°C respectively. The fish were found in areas with relatively few aquatic plants, over gravel or sand bottoms, often in the vicinity of submerged logs.

In 2002 M. irianjaya was collected in a number of tributaries of the Saengga River (Bofura Creek, Siripa Creek, Burma Hill Creek, Texas Creek and Mai Creek.) situated on the north coast of the Bomberai Peninsula. Water conditions recorded at these sites were pH 5.0-6.3, Temperature 25-26.5°C, and Conductivity10-60 µS/cm.

Remarks
Live specimens were collected for the aquarium hobby in 1982 from near the village of Fruata by Heiko Bleher.

Literature
Allen G.R. (1985) Three new rainbowfishes (Melanotaeniidae) from Irian Jaya and Papua New Guinea. Revue française d'Aquariologie 12 (2): 53-62.

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

Burnett J.B., M. Davies and G. Taylor (2003) Flora and Fauna Survey of the Tangguh LNG Site Papua Province, Indonesia. P.T. Hatfindo Prima, Bogor.

Pouyaud L. (2007) Expedition Papua 2007 10 mai - 14 juin. Rapport de mission. IRD Indonesie, departement resources vivantes - UR 175 pp 43.

Adrian R. Tappin
Updated March, 2016