Northern Rainbowfish
Melanotaenia affinis
One of the first rainbowfish in the hobby, now available in several wild forms.
About
The Northern Rainbowfish (Melanotaenia affinis) holds a small piece of hobby history as one of the earliest rainbowfish to be imported in meaningful numbers, and it remains a solid representative of the group today. Native to New Guinea, it reaches a respectable adult size that puts it firmly in the mid-to-large community fish category. Several geographical variants exist, with the most commonly traded being the wide-ranging standard form. The Pagwi form, known only from a Sepik River tributary, and the Bluewater Creek form, collected from a single site near Madang in Papua New Guinea, occasionally surface in specialist circles. All three look quite similar at a glance, differing mainly in subtle color and pattern details. In terms of behavior, this species is peaceful by intent but can inadvertently stress smaller or slower tankmates through its active, fast-moving nature. Keeping a group of at least six to eight individuals is strongly recommended. A larger shoal not only reduces skittishness but also encourages males to display their best colors when competing for attention. Good companions include similarly sized rainbowfish, characins, danios, barbs, and Corydoras catfish. The species is an egg scatterer that breeds readily under the right conditions, making it an approachable project for keepers with some rainbowfish experience already under their belt.
Similar species
Other fish you might consider
Good tank mates
Species that tend to coexist peacefully with Northern Rainbowfish
From the same region
Share the same natural habitat. Great for a biotope-themed tank
Frequently asked questions
- How big does the Northern Rainbowfish get?
- The Northern Rainbowfish reaches about 2.5–5" as an adult.
- What size tank does the Northern Rainbowfish need?
- A minimum of 29 gallons is recommended for the Northern Rainbowfish, with more room needed for a proper group.
- What water parameters does the Northern Rainbowfish need?
- The Northern Rainbowfish does best with a temperature of 68–86°F, a pH of 6.5–8, hardness around 6–20 dGH.
- Is the Northern Rainbowfish aggressive?
- The Northern Rainbowfish is generally peaceful and suits a community tank with similarly calm tankmates.
- What does the Northern Rainbowfish eat?
- The Northern Rainbowfish is an omnivore. It does well on a varied diet of quality flake or pellet plus occasional frozen or live foods.
- How long does the Northern Rainbowfish live?
- With good care, the Northern Rainbowfish typically lives 5-8 years.