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New Guinea rainbowfish

Melanotaenia affinis

Also known as Northern Blue Rainbow

FreshwaterFish

New Guinea rainbowfish (Melanotaenia affinis)
Imperial Tropicals · Used with permission

Care at a glance

Temperature
68–86°F
20–30°C
pH
7.0–8.0
Adult size
4.7 in
12 cm
Minimum tank
30 gal
115 L
Temperament
Peaceful
Social behavior
Schooling
Swim level
Middle
Difficulty
Easy
Breeding
Egg depositor · Hard
Rarity
Common
Family
Melanotaeniidae
Origin
New Guinea

Overview

The New Guinea rainbowfish is an active schooling fish that cruises the middle of a larger community tank. It is easy to keep.

Did you know

Male New Guinea rainbowfish flash a bright stripe down the forehead during courtship and feeding. It flickers on and off, almost like a switch, and few aquarium fish do anything like it. The display is strongest first thing in the morning, when they usually spawn.

Caring for the New Guinea rainbowfish

Give New Guinea rainbowfish a group of six or more and a tank of 30 gal (115 L) or larger. They are active swimmers, so a long footprint suits them better than a tall one. Provide good flow and plenty of room to swim.

They tolerate a broad temperature range, from 68 to 86°F (20 to 30°C), so heating is rarely a problem. Keep the pH at 7.0 to 8.0, on the neutral to alkaline side. Feed a varied diet of quality flake, small pellets and frozen foods to bring out their color.

New Guinea rainbowfish stay peaceful and suit a larger community of similar-sized fish. Males develop deeper color and a taller body than females. They hang their eggs on fine plants over a long spawning period rather than in one batch, and breeding them is hard.

Good to know

The New Guinea rainbowfish is a member of the rainbowfish family Melanotaeniidae. With good care, it commonly lives around five years. It is also known as the northern blue rainbow.

In the wild

The New Guinea rainbowfish lives in clear, flowing rivers and streams across New Guinea, often in fairly hard, alkaline water. These are open, well-oxygenated waters with current.

Weekly picks

Tank mates

The New Guinea rainbowfish is a peaceful, schooling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a New Guinea rainbowfish need?

A New Guinea rainbowfish needs at least 30 gal (115 L). It spends most of its time in the middle.

What temperature and pH does a New Guinea rainbowfish need?

A New Guinea rainbowfish is comfortable at 68–86°F (20–30°C) with a pH of 7.0–8.0.

What does a New Guinea rainbowfish eat?

A New Guinea rainbowfish eats a varied diet of quality flake, small pellets and frozen foods. The variety brings out its color.

How big does a New Guinea rainbowfish get?

An adult New Guinea rainbowfish reaches about 4.7 in (12 cm).

Does a New Guinea rainbowfish need a group?

Yes. A New Guinea rainbowfish is a schooling species and should be kept in a group, not singly.

How can you tell a male New Guinea rainbowfish from a female?

Males develop deeper color and a taller body than females.

How does a New Guinea rainbowfish breed?

New Guinea rainbowfish hang their eggs on fine plants over a long spawning period, not in one batch. Breeding them is hard.

Related species