Fasin rainbowfish

Melanotaenia fasinensis

Also known as Fasin Creek rainbowfish, Fasinensis rainbow

FreshwaterFish

Fasin rainbowfish (Melanotaenia fasinensis) — The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature: 75–84°F (24–29°C)
pH: 6.8–8.0
Adult size: 5.4 in (13.8 cm)
Minimum tank: 53 gal (200 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Medium
Breeding: Medium
Rarity: Rare
Origin: Fasin Creek, Klasafet region, Bird's Head Peninsula, West Papua
Family: Melanotaeniidae

Overview

A large, energetic rainbowfish that needs length more than anything, so keep a school of six or more in a long tank and let the males own the open midwater. It is peaceful despite its size and bustle, and does best with other sturdy, calm fish that can keep up, such as barbs, larger rainbowfishes, and peaceful catfish. Feed a generous, varied diet of flake and granules with frozen bloodworm, daphnia, and brine shrimp. Give a group at least 200 liters, favoring a long tank over a tall one.

In the wild

This rainbowfish lives in Fasin Creek, in the Klasafet karst country of the Bird's Head Peninsula, clear limestone-fed water carrying dissolved minerals. Match that with neutral to alkaline, moderately hard water at a pH of 6.8 to 8.0 and 24 to 29 degrees Celsius. Give it current, a sandy bottom, and open swimming room, with plants around the edges.

Good to know

Melanotaenia fasinensis, family Melanotaeniidae, was described by Kadarusman, Paradis, and Pouyaud in 2010, and it reaches about 13.8 centimeters, one of the larger rainbowfishes discovered in recent decades. Males are olive-backed with a dark band along the flank. Breeding is of medium difficulty, in the standard rainbowfish pattern of daily egg-scattering onto plants or mops.

Did you know

The scientific paper that named this creek fish in 2010 also reported the rediscovery of the Ajamaru Lakes rainbowfish, a species that had gone unrecorded since the 1950s and was feared lost.