Wanam Rainbowfish

Melanotaenia wanamensis is an endangered rainbowfish known only from Lake Wanam, a small crater lake in the Markham Valley of Papua New Guinea. The lake has been severely impacted by introduced predators and invasive species, making captive populations in hobbyist aquariums an important conservation resource. Mature males are impressive fish, reaching up to 14 cm and developing a stunning deep blue-green body with reddish-gold scale edges and vivid orange finnage.

This species requires warmer, slightly alkaline, hard water reflecting its volcanic lake origin. It is one of the larger rainbowfish species and needs a spacious aquarium of at least 250 litres. Because of its conservation status, dedicated keepers are encouraged to maintain accurate records of their breeding groups and contribute to studbook programs where available.

Melanotaenia wanamensis is a moderately demanding species to maintain at peak condition due to its specific water chemistry requirements, but it rewards dedicated care with exceptional beauty and fascinating behaviour. It is best kept in a species group or with a few large, peaceful companion species.

Water: Hard, alkaline water; pH 7.5–8.5, temperature 25–30°C, GH 12–20; stable chemistry is critical. Tank: Minimum 250 L; strong filtration; open swimming space with minimal decor to reduce aggression between males. Feeding: Quality flake and pellets; enrich with live and frozen brine shrimp and daphnia; feed generously. Breeding: Egg scatterer; separate spawning tank recommended; maintain studbook records due to conservation status. Compatibility: Best kept as a species group; only house with other large, non-aggressive companions.