North New Guinea Rainbowfish

Nematocentris magnificus (placed historically within Melanotaenia) is a large and boisterous rainbowfish from the northern coastal rivers of Papua New Guinea. It is a powerful, fast-moving species with a relatively elongated body, a bold dark mid-lateral stripe, and vivid orange to orange-red finnage that is particularly intense in dominant males. The body itself is silver-blue with a scattered iridescent quality.

This species is not widely available in the hobby but appears sporadically through specialist importers. It requires a very spacious aquarium with excellent water movement and filtration, as it is an active species that covers a great deal of distance in the wild. Despite its relatively large adult size, it is entirely peaceful and does not threaten other fish.

Nematocentris magnificus breeds in the typical rainbowfish manner and produces moderate-sized spawns. Its fast-growing fry are proportionally robust. The species does best in groups of at least five or six, where male display behaviour and social structure are most naturally expressed.

Water: pH 7.0–8.0, temperature 23–28°C, moderately hard; powerful filtration and brisk current. Tank: Minimum 200 L; very open swimming space; plants and driftwood at perimeter only. Feeding: Quality pellets and flake; supplement generously with live and frozen foods. Breeding: Standard egg-scattering on plants or mops; fry robust and fast-growing. Compatibility: Peaceful; excellent in large rainbowfish communities; avoid housing with very timid species.