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Melanotaenia herbertaxelrodi

Melanotaenia herbertaxelrodi
Lake Tebera Rainbow
Melanotaenia herbertaxelrodi belongs to a group of rainbowfish species, which inhabits the Highland drainage systems of the Kikori and Purari Rivers. This group contains two other species, M. monticola and M. lacustris. Gerald Allen believes that the three species are probably derivatives of the same ancestral stock of M. goldiei, which ranges widely in the lowland and foothill areas of southern New Guinea. Melanotaenia herbertaxelrodi is most closely related to M. monticola from the upper Purari System near Mendi, about 200 km upstream from the Lake Tebera Basin. Males are mainly bright yellow (sometimes greenish) with a blue-black, mid-lateral line. The dorsal, anal, and caudal fins can be red or yellow. During spawning the male has an intense blue or white stripe from the first dorsal fin extending down over the nape to the tip of the snout, while the whole head can become almost black. The rest of the body is bright yellow with reddish fins.

Melanotaenia herbertaxelrodi may reach a maximum size of 12 cm, but usually less than 10 cm. Males are typically deeper bodied than females and develop a high forehead and an angulated breast profile with increased growth. The body begins to deepen in males after a length of 45~50 mm SL is attained or at about the onset of sexual maturity. In addition, the middle portion of the first dorsal fin is much longer in males and the posterior outline of the second dorsal fin is more pointed than in females, although this difference is not nearly as apparent as in many other members of the Melanotaenia genus.