Melanotaenia aruensis

Species Summary
Melanotaenia aruensis males are grey-brown dorsally on the head, nape, and adjacent anterodorsal portion of the body; upper rear portion of cheek and adjacent portion of operculum pale yellow with metallic reflection; iris mostly pale yellow; posterior two-thirds of upper half of body bluish grey with narrow bronze margin around each scale and bronze stripe between each horizontal scale row; lower half of head and body white to pale grey; dorsal and caudal fins semitranslucent grey, second dorsal fin with relatively broad whitish margin; anal fin dusky grey with bronzy suffusion basally and broad white outer margin; pelvic fins greyish except white at base and near posterior tip; pectoral fins translucent. Freshly collected live fish photographed in an aquarium were similar in appearance except the membranous portion of the first dorsal fin is orange and orange colouration is present basally on the second dorsal fin and very prominent on the basal half of the anal fin. The female is similar to the male, except colours are less vivid, particularly the orange and bronzy hues. Individuals from Kobroor Island lack the broad white margins on the dorsal and anal fins.

This species was named aruensis with reference to the Aru Islands type locality.

Distribution & Habitat
Melanotaenia aruensis is currently known from two locations, the type locality on Trangan Island and a small river on southern Kobroor Island. The two locations are separated by a distance of 34 km, and current day saltwater barriers in the form of Sungai Workai and Sungai Maikoor. The type locality is situated in luxuriant rainforest on the downstream side of a spectacular 75 m-long limestone tunnel. The stream was approximately 10-12 m wide with depths ranging from about 0.5-2.0 m. The water was relatively clear and slow-flowing with a rocky limestone bottom and abundant cover mainly in the form of submerged fallen tree limbs. The site on Kobroor Island, also lined by luxuriant forest was 15-20 m wide, 1-3 m deep, clear, and slow flowing. The margins of the channels were characterised by abundant, partially submerged terrestrial plants, which offered abundant shelter for small fishes. Temperature, pH, and conductivity values of 26.5°C, 8.03, and 144 µS respectively were recorded in January 2013. The species was common at both sites.

Literature
Allen G.R., R.K. Hadiaty, P.J. Unmack and M.V. Erdmann (2015) Rainbowfishes (Melanotaenia: Melanotaeniidae) of the Aru Islands, Indonesia with descriptions of five new species and redescription of M. patoti Weber and M. senckenbergianus Weber. aqua, International Journal of Ichthyology 21(2): 66-108.

Adrian R. Tappin
June, 2015