Dark Rainbowfish | Melanotaenia nigrans
Rainbowfish / Melanotaeniinae / Dark Rainbowfish
Profile: Dark Rainbowfish
Melanotaenia nigrans Physical description: An elongated, laterally compressed species with a large eye. There are two dorsal fins, an anal fin with a long base, and a slightly forked caudal fin. The back is yellow-gray and the belly is beige-white. The flanks are marked with a violet to green iridescence. A dark, black band runs from the snout through the eye and to the caudal fin. Bordering this marking are regions of whitish-yellow. The fins, except for the caudal, are violet in color with dark borders. The caudal fin may be reddish-yellow.
Size/Length: Males to 2.8" (7 cm), females to 2.4" (6 cm)
Similar species: Melanotaenia fluviatilis, M. maccullochi
Habitat: Inhabits freshwater rivers and occasionally visits brackish water estuaries. Eastern Australia; from Sydney to the Cape York Peninsula; and Papua New Guinea.
S: middle, top
Aquarium: A tank measuring 32" (81 cm) with a capacity of 30 gallons (114 L) is sufficient. Plant along the edges of the tank and leave an open swimming area. The lighting should be bright and a sandy or fine gravel substrate can be used.
Water chemistry: pH 6.7-7.8 (7.2), 8-15 dH (10), 64-77°F (18-25°C). Salt can be added, anywhere from a 0.5-1.5% addition is acceptable.
Social behavior: An active, but peaceful schooling species that should be kept in groups of five or more.
Suggested companions: other Rainbowfish, Barbs, Danios, tetras, Gouramis, Corydoras, Livebearers
FOOD: Live; insect larvae, crustaceans, worms, insects; flakes
SEX: Males are larger and more colorful with pointed first dorsal fin. Females lack the black edging to the fins.
Breeding techniques: As for M. fluviatilis. The parents will ignore the eggs.
Breeding potential: 5. An easily bred fish.
Remarks: In tanks without males, a female may lay mature eggs which will not hatch.
Difficulty of care: 4. This robust species is suitable for a community tank.