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.

Recent articles about fish

Overfishing may hurt Amazon forest trees
(2/5/2008) Overfishing is reducing the effectiveness of seed dispersal by fish in the Brazilian Pantanal, reports Nature. The research suggests that fishing practices can affect forest health.

Scientists find fish that literally lives in trees
(10/17/2007) Scientists have found a fish that literally lives in trees, according to research published in The American Naturalist and highlighted in New Scientist Magazine.

Piranhas originated when Amazon was flooded by seawater
(12/4/2007) South America's piranha family of fish -- notorious as eaters of flesh -- can be traced back to a single ancestor which dispersed when the Amazon was flooded by seawater some five million years ago, report researchers from the Institut de Recherche Pour le Developpement (IRD). Today piranhas are exclusively freshwater fish found from the Orinoco River basin in Venezuela to the Parana in Argentina.

Copyright Rhett Butler 1994-2009

The copy for fish.mongabay.com was written in 1994-1995. Therefore some information such as scientific names may be out of date. For this, I apologize. Feel free to send corrections to me.