New Guinea rainbowfish

Geographic Origin and Biotope: New Guinea (Northern). Populates mountain streams, crystal clear rivers and rainforest pools both in lowland and foothill areas.

Taxonomy and Morphology: North New Guinea Rainbowfish (Melanotaenia affinis). Classic rainbowfish with a laterally highly compressed rhomboidal body (humped back in old males) and double contiguous dorsal fin.

Social Behavior: Lively and peaceful gregariousness (minimum 6-8 specimens). Moves in a school in the upper water column. Males engage in choreographic "sparring" (without physical damage) expanding their fins to visually dominate.

Coloration and Sexual Dimorphism: Extremely variable depending on the capture zone (morph "Pagwi", "Bundi"). Generally sports a dark olive body superiorly and yellow/gold inferiorly, cut by a dense lateral black band. Males much larger and more colorful than females.

Aquarium Setup: Minimum 100 cm (40 inches) aquarium. Loves open water for frantic swimming, therefore plant only along the back or side glass (Vallisneria is excellent). Strong current appreciated. Intense lighting will bring out the iridescent reflections.

Diet and Feeding: Surface insectivore. The mouth is upturned. Provide floating foods (very high quality flakes, freeze-dried) and live/frozen food (Daphnia, White mosquito larvae). Struggle to eat foods deposited on the bottom.

Water Quality: Very tolerant, but expresses itself best in slightly hard and neutral/alkaline waters. Requires excellent water quality through regular massive changes (very sensitive to high nitrates).

Compatibility and Tankmates: The perfect community fish for Asian or Australian aquariums. Coexists very well with other Melanotaenia, Glossolepis, Loaches, and huge schools of Danios/Rasboras. Absolutely harmless.

Aquarium Reproduction: Continuous Spawners. After a frantic courtship rite at dawn, they scatter adhesive eggs among the leaves of Java moss or synthetic mops. Parents will ignore the fry, which require infusoria and powdered food.

Risks and Diseases: Mycobacteriosis. All Melanotaenias, if exposed to prolonged nitrate spikes, can develop "Fish Tuberculosis" (Mycobacterium marinum): they lose colors, become emaciated and develop ulcers (Incurable).