Order Atheriniformes
Family Melanotaeniidae
Continued…
Genus Melanotaenia.
— Duboulay’s Rainbowfish — Melanotaenia duboulayi [Castelnau, 1878]. Synonym: Atherinichthys duboulayi. (English: Duboulay’s Rainbowfish, Crimson Spotted Sunfish). Australia, coastal basins of New South Wales and southern Queensland. 8-11 cm. Depending on geographical origin, there are various color morphs. The body is mostly silvery-blue or green, with a deep bluish or yellow tint. Scale rows have narrow yellow lines, with edges colored from bright orange to red. A bright crimson spot is prominent on the gill cover.
Characterized by yellowish-red, red-spotted fins with a wide black border on the dorsal, anal, and anterior edge of the pelvic fins. These dark margins become intensely black in males during the spawning season. Red-orange dashes are scattered across the grayish fins, and blackish dots appear on the caudal fin. Males are brighter, usually larger and lighter in color, with a higher body profile. The tips of the dorsal and anal fins are pointed and colored, whereas in females they are rounded and transparent.
A very similar species is M. fluviatilis, which is almost identical externally (except for a more pointed snout). Geographical color variations: — Melanotaenia duboulayi “Albert River”; — Melanotaenia duboulayi “Burnett River”; — Melanotaenia duboulayi “Colosseum Creek”; — Melanotaenia duboulayi “Gin Gin Creek”; — Melanotaenia duboulayi “Kangaroo Creek”; — Melanotaenia duboulayi “Kolan River”; — Melanotaenia duboulayi “Maroochy River”; — Melanotaenia duboulayi “Richmond River”;— Melanotaenia duboulayi “Snapper Creek”;
Shoaling fish that require plenty of swimming space, areas of dense vegetation along the edges, and peaceful tankmates. Prefer middle water levels. In their natural habitat, fish feed mainly on surface insects, but also on bottom crustaceans and algae. The female lays several eggs per day, which are fertilized by the males. The eggs are held by long, thin threads among fine-leaved plants or floating plant roots. Young fish grow rapidly and reach maturity within a year after hatching. pH 7-7.5; dH 10-15°; T 22-26°C.
— Goldie River Rainbowfish — Melanotaenia goldiei [Macleay, 1883]. Synonym: Aristeus goldiei. (English: Goldie River Rainbowfish). Southern New Guinea. 10 cm, females 8 cm. They feature a characteristic copper sheen on the upper half of the body with a creamy-white color on the lower half. The lateral stripe is intermittent, dark blue or blackish, about 2 scales wide, most visible below the dorsal fin and at its widest point on the caudal peduncle. There is a narrow copper or orange stripe between each scale row on the upper half of the body. Males are brighter, with a higher body profile. The first dorsal fin is higher than that of the female and, when folded, reaches past the origin of the second dorsal fin.
Similar to Melanotaenia iris, but in this species the lateral line runs along the entire body and is of uniform width. Geographical color variations: — Melanotaenia goldiei “Aru 2”; — Melanotaenia goldiei “Aru 4”; — Melanotaenia goldiei “Dekai Village”. Metallic blue coloration with yellow-red fins. The body coloration of adult males during courtship turns from purple to violet. Females are colored similarly; — Melanotaenia goldiei “Tapini”; — Melanotaenia goldiei “Timika”; Peaceful, undemanding. Requires an aquarium with finely divided plants, best planted along the sides and back walls. Shoaling fish. Occupy the middle water layers. Keep with reasonably sized, peaceful tankmates. pH 7.0-7.8; dH 3-15°; T 20-26°C.
— Slender Rainbowfish — Melanotaenia gracilis [Allen, 1978]. (English: Slender Rainbowfish). Western Australia, Edward, Drysdale, and Carson River basins. 8 cm. This species has a slightly slenderer body than most other rainbowfishes and is laterally compressed. Olive coloration with greenish tints, pearlescent sheen, and a wide brownish-coffee stripe along the body. The lower half of the body is iridescent lavender. Fins are transparent or slightly pink, with a bright red border on the dorsal and anal fins. Red spots are present on the tips of the outer rays of the caudal fin.
With age, males acquire a beautiful yellow-orange attire with a longitudinal dark stripe featuring a bluish sheen. In dominant males, this stripe dissolves into the yellowish background, replaced by a bright blue-green crest-like line running from the upper lip across the head and onto the first dorsal fin. This is especially prominent during morning spawning displays.
Females are paler and fuller-bodied. When young, fry are silvery with a slight golden hue and a dark horizontal band. These fish resemble Melanotaenia nigrans, which has a more pronounced lateral line. Geographical color variations: — Melanotaenia gracilis “Drysdale River”;
Fast and active, requiring elongated aquariums planted with aquatic plants along the perimeter to thrive. A school of these melanotaenias gets along wonderfully with any non-aggressive fish. Occupy the middle water layers. The fish get very frightened during capture and transfer. Some specimens may experience spasms leading to body curvature in various planes. Fortunately, most of these partially paralyzed fish return to normal within a day or two without lasting health consequences. Nevertheless, they should not be subjected to frequent netting and transfers. Lifespan up to 4 years. pH 7-8; dH 10-15°; T 24-28°C.
— Sorong Rainbowfish — Melanotaenia fredericki [Fowler, 1939]. Synonym: Charisella fredericki. (English: Sorong Rainbowfish). New Guinea, north of Sorong, in slow-flowing, clear rainforest streams. 9-11 cm. The main color of the upper half of the body is pinkish-lilac with blue scales, featuring broad yellow striations on the lower half. Adult fish sometimes show yellow coloration only on the scale margins. Fins are mostly semi-transparent, but the dorsal, anal, and caudal fins have yellow or red tints. Males are brighter, with a higher body profile. The first dorsal fin is higher than that of the female and, when folded, extends past the origin of the second dorsal fin.
Identification: Genus Melanotaenia — Melanotaenia duboulayi, fredericki, goldiei, gracilis.
Melanotaenia fluviatilis, herbertaxelrodi, irianjaya, japenensis, kamaka.
Melanotaenia batanta, Melanotaenia boesemani, caerulea, catherinae. 
