Order Atheriniformes ( Atheriniformes )
Family Melanotaeniidae ( Melanotaeniidae )
Continued…
Genus Melanotaenia — Melanotaenia.
— North New Guinea Rainbowfish — Melanotaenia affinis [Weber, 1908]. Synonym: Rhombatractus affinis. (Eng- North New Guinea Rainbowfish, Rhombosoma sepikensis). Distributed across a large area in the northern regions of New Guinea, Sepik, Ramu, Taritu rivers. Size 10-12 cm, with a body depth of 3-4 cm. Egg-shaped and laterally compressed body, covered with large scales. Body depth increases with age. Their coloration varies depending on the place of origin and water conditions. There may also be variations in body width and head shape.
The body is olive-green with a bronze-yellow back, sides often with a series of narrow orange stripes between each row of scales, belly is white. A dark blue stripe runs along the sides of the head, wider on the caudal peduncle, often pale or interrupted in the pectoral fin area. In the caudal area, there are several red or orange stripes. Fins range from whitish-translucent to yellowish. The anal fin and often the dorsal fin in adult males are bright yellow-orange.
Males are more intensely colored, especially with brighter orange stripes and a dark middle stripe, with a higher body. The ends of the dorsal and anal fins are pointed, larger, and colored, whereas in females they are rounded, smaller, and translucent. The unpaired fins of females are either colorless or have a faint yellow tint. These sexual characteristics increase with age. Similar to Melanotaenia goldiei, but they have a less pronounced lateral stripe, and the anal fin and second dorsal fin in adult males are orange or pink.
Geographic color variations: — Melanotaenia affinis “Pagwi” – from mountainous regions, where they live in the upper reaches of the Sepik River. They have a greenish to olive upper body color and a light belly. The lateral middle stripe is blue and clearly visible. Above and below the central line are bright red-orange stripes. In the lower and posterior part of the body, there is a yellow stripe. The head is sharper; — Melanotaenia affinis “Blue Water Creek” – upper body is greenish-blue with a silvery sheen, belly is whitish. The lateral middle line is blue-black, bordered below by a wide white margin; — Melanotaenia affinis “Bonggo”; — Melanotaenia affinis “Lae”;
Peaceful, undemanding. Aquarium with fine-leaved plants, best planted along the side and back walls. Keep in schools in an aquarium with sufficient swimming space, dense vegetation, and peaceful tank mates. Prefer middle water levels. Transparent water is required.
Quite tolerant of water hardness and alkalinity, but cannot withstand high levels of nitrites or nitrates. Require powerful filtration and water oxygenation. In nature, they are carnivorous, feeding on invertebrates in the water or on the water surface. Reach sexual maturity by the end of their first year at a length of 5-6 cm. pH 6.5-8.0; dH 6-15°; T 20-27°C.
Identification: North New Guinea Rainbowfish — Melanotaenia affinis.
— Yakati Rainbowfish — Melanotaenia angfa [Allen, 1990]. (Eng- Yakati Rainbowfish). Western New Guinea (Irian Jaya), Yakati River. 12 cm. Bright yellow or light orange fish (including fins) with a narrow black stripe interrupted along its entire length by narrow yellow gaps. Males are larger, bigger, and higher-bodied than females, and more brightly colored. The first dorsal fin of males is larger and higher, extending past the base of the second dorsal fin when folded.
Very similar to M. herbertaxelrodi, but larger and having 20-22 rays in the anal fin. (Melanotaenia herbertaxelrodi only has 17-18 rays). Aquarium with floating plants, plants along the sides, driftwood. Feels better and more confident in a school. It is advisable to keep at least 4-5 specimens. Free swimming space is required. Eats all types of food. pH 6.5-7.5, T 24-26°C.
— Arfak Rainbowfish — Melanotaenia arfakensis [Allen, 1990]. (Eng- Arfak Rainbowfish). Western New Guinea, Prafi River. 8-10 cm. Main body color is light purple with a silvery sheen, a horizontal wide blue-black stripe in the center is interrupted by narrow bars. Narrow yellow-orange stripes between each row of scales on the sides of the body. Fins are translucent with a bluish tint and pinkish-lilac shading. The second dorsal fin has a narrow black and white stripe in its upper part. Caudal fin with black upper and lower rays. Males are larger, slimmer, and brighter. Prefer current. Shoaling fish.
— Western Rainbowfish — Melanotaenia australis [Castelnau, 1875]. Synonyms: Melanotaenia splendida australis, Neoatherina australis. (Eng- Australia Rainbow, Western Rainbowfish). Western Australia. 8-10 cm. Their color, especially the fins and the intensity of the lateral stripe, is extremely variable depending on geographical location. Lilac and red colors predominate in their attire.
Body coloration usually consists of one or two wide, dark lateral stripes and rows of narrow red stripes between scale rows. A key feature is the blackish zigzag lines at the bottom of the body, just above the anal fin. These lines can be pronounced or barely noticeable. Distinguishing them from other Melanotaenia species at a young age is very simple: the main body color of the fish is light lilac with two dark longitudinal stripes, with the lower stripe often blurred and shortened. Fin colors vary from almost colorless to dark red or bright red with green spots. Most importantly, the coloration of the tail and the rear part of the anal and dorsal fins can change from fiery red to bright cherry.
The main body coloration of adult fish ranges from light olive-brown to dark brown. The back is darker, the chest and belly are lighter. From the rear edge of the eye to the base of the caudal fin, some populations have a wide black stripe or 3-5 thin black longitudinal lines. Fins range from yellowish to reddish, often with red spots. With age, the color saturation reaches its peak. At the same time, more and more bright red color appears. Males are easily distinguished from females by the brightness of their body coloration and more elongated dorsal fin rays.
Fish from Kimberley have more yellow in their fin coloration, reddish dots on the dorsal and anal fins, and dark spots on the caudal fin. Specimens from Pilbara are distinguished by red tones in their fin coloration. On the body, among the black stripes and zigzags, 2 red lines stand out, framing the wide median stripe.
Geographic color variations: — Melanotaenia australis “Blackmore River”; — Melanotaenia australis “Cambolgie Creek”; — Melanotaenia australis “Drysdale River” – Has a shorter body length and a distinctive double black lateral stripe. In males, the fins are red, and the back is steel-colored; — Melanotaenia australis “Carrawine Gorge”; — Melanotaenia australis “King River”; — Melanotaenia australis “Reynolds River”; — Melanotaenia australis “Upper Katherine River”; — Melanotaenia australis “Waterplant Creek”;
Best kept in a group of 4-6 specimens. In the aquarium, at the ends and near the back wall, there should be plant shelters where rainbowfish love to hide, leaving swimming space in the front. Filtration, powerful aeration (sensitive to low oxygen levels), and weekly water changes are necessary. The water current should not be strong. If necessary, water can be salted up to 5%. They can be fed live, vegetable, and artificial foods. Fry grow quickly and reach 3 cm by 12 weeks. T 22-27°C; dH 7-20°, pH 6.3-8.0.
Melanotaenia batanta, Melanotaenia boesemani, caerulea, catherinae.
Description of the family Melanotaeniidae and the genus Melanotaenia. 
