Red Rainbowfish (Glossolepis incisa)

One of the most intensely red freshwater rainbowfish, with mature males developing brilliant scarlet colour, a powerful high-backed body shape, and impressive schooling presence.

The Red Rainbowfish, Glossolepis incisa, is a striking freshwater rainbowfish native to Lake Sentani in Papua, Indonesia. It is also known as Salmon Red Rainbowfish, New Guinea Rainbowfish, or simply Red Rainbow.

Mature males are the reason this species has become such an iconic aquarium fish. As they grow and settle, males can develop an intense red to scarlet body colour and a noticeably deeper, higher-backed profile. Females are more subtle, typically showing olive, bronze, silver, or yellowish tones.

Red Rainbowfish are active, social swimmers rather than slow centerpiece fish. Their best appearance comes from a proper group in a long aquarium with open swimming space, good water quality, and a varied diet.

Why this fish stands out

• One of the strongest true red colours available in a freshwater community fish
• Mature males develop an impressive deep-bodied, high-backed shape
• Native to Lake Sentani in Papua, Indonesia
• Large, active rainbowfish with strong schooling presence
• Excellent centerpiece school for larger planted aquariums
• Peaceful enough for many appropriately sized community fish

Best for

• Rainbowfish enthusiasts
• Medium to large planted aquariums
• Active community tanks
• Aquarists looking for a genuinely red freshwater schooling fish
• Display aquariums with open swimming space
• Customers looking for Red Rainbowfish in Canada

Topick Aquarium Insight

Red Rainbowfish are one of those fish that are often underestimated when young. Juveniles and newly arrived males may look bronze, orange, or only lightly red, while a mature, confident male can look like an entirely different fish.

Age, sex, social hierarchy, diet, lighting, stress level, and aquarium conditions all influence colour. This is why buying a young Red Rainbowfish should be viewed as buying a fish with development potential rather than expecting full adult red colour immediately.

They also look much better in a group. A single male may survive, but keeping several rainbowfish together encourages natural interaction, display behavior, movement, and stronger overall visual impact.

Male vs Female Red Rainbowfish

Red Rainbowfish show strong sexual dimorphism as they mature.

• Mature males: intense red to scarlet body colour, larger size, and increasingly deep high-backed body shape
• Females: generally olive, bronze, yellowish, or silver-toned and more streamlined
• Young males: may initially look similar to females and develop red colour gradually
• Dominant males: often display the strongest colour when comfortable in a group

Customers purchasing juveniles should expect colour and body shape to continue developing with maturity.

Behavior & Group Size

Red Rainbowfish are peaceful but very active schooling fish. They spend most of their time swimming through the middle and upper portions of the aquarium.

We recommend keeping at least 6 fish, with 8 or more preferred when aquarium size allows. A proper group helps reduce nervous behavior and encourages males to display naturally.

Because they are fast and energetic, they can intimidate very slow, shy, or extremely small fish even without intentional aggression.

Tank Setup

Red Rainbowfish need horizontal swimming space. A long aquarium is much more suitable than a tall aquarium with the same water volume.

• Minimum recommended tank: approximately 55 gallons for a proper adult group
• 4-foot aquarium or longer strongly preferred
• Keep open swimming space through the middle and front of the aquarium
• Plants can be concentrated along the sides and background
• Good filtration and oxygenation recommended
• Moderate water movement works well
• Secure lid recommended as rainbowfish can jump

A planted aquarium works extremely well, but avoid filling the entire tank with dense hardscape. These fish need room to accelerate, school, chase, and display.

Water Parameters

• Scientific Name: Glossolepis incisa
• Older / Alternate Scientific Spelling: Glossolepis incisus
• Common Names: Red Rainbowfish, Salmon Red Rainbowfish, New Guinea Rainbowfish
• Origin: Lake Sentani, Papua, Indonesia
• Temperature: 22–26°C
• pH: approximately 7.0–8.0
• Hardness: moderate to moderately hard water preferred
• Adult Size: approximately 12–15 cm
• Temperament: Peaceful and active
• Diet: Omnivore
• Care Level: Intermediate

Red Rainbowfish are better suited to neutral-to-alkaline, moderately mineralized water than very soft, strongly acidic conditions. As always, stable water and consistent maintenance are more important than constantly adjusting parameters.

Feeding for Strong Red Colour

Red Rainbowfish are enthusiastic feeders and accept a wide range of foods. A varied diet is especially important if your goal is strong adult colour and body development.

• High-quality rainbowfish or tropical pellets
• Quality flakes
• Frozen brine shrimp
• Frozen daphnia
• Krill-based foods
• Bloodworms in moderation
• Spirulina or vegetable-containing foods

Carotenoid-rich foods such as quality krill-based diets can help support natural red pigmentation, but genetics, sex, maturity, and overall condition remain the major factors determining final colour.

Feeding more food does not automatically create a redder fish. Good body condition without obesity is the goal.

Tank Mates

Red Rainbowfish work best with peaceful to moderately active fish that are large and confident enough to share their swimming space.

• Boesemani Rainbowfish
• Turquoise and other medium-large rainbowfish
• Larger peaceful barbs
• Medium-sized peaceful tetras
• Danios
• Corydoras
• Peaceful larger catfish
• Suitable peaceful gouramis in spacious setups

Avoid extremely timid nano fish, very slow long-finned fish, and aggressive predators. The issue with tiny tank mates is often the Red Rainbowfish's speed and size rather than aggression.

Red Rainbowfish vs Boesemani Rainbowfish

Red Rainbowfish and Boesemani Rainbowfish are both medium-large, active schooling rainbowfish, but their appearance is very different.

• Red Rainbowfish: mature males develop an almost full-body red to scarlet appearance
• Boesemani Rainbowfish: famous for the contrasting blue front half and yellow-orange rear half
• Both: need groups, open swimming space, stable water, and a quality varied diet

For aquarists specifically looking for the strongest red visual impact in a larger freshwater community, mature male Red Rainbowfish are hard to confuse with any other common rainbowfish.

Breeding

Red Rainbowfish are egg scatterers. Conditioned adults may spawn repeatedly among fine-leaved plants or spawning mops.

Eggs are laid over a period of days rather than in one large single spawn. For intentional breeding, eggs or spawning mops are normally moved away from the adults and fry are started on very small foods before progressing to newly hatched baby brine shrimp.

Canada-Wide Live Fish Shipping

Red Rainbowfish is available from Topick Aquarium in Canada when in stock. Local pickup is available in Markham, Ontario, and Canada-wide live fish shipping may be available depending on weather, route, size, and livestock condition.

Important Note

Young Red Rainbowfish may not arrive looking fully red. Full male colour develops with age, genetics, social status, nutrition, and stable aquarium conditions.

If you are purchasing this species specifically for its famous red appearance, remember that females naturally remain much less red than mature males.

FAQ

What is a Red Rainbowfish?
Red Rainbowfish is a freshwater rainbowfish from Lake Sentani in Papua, Indonesia. Its scientific name is Glossolepis incisa, and mature males are famous for developing intense red coloration.

Is the scientific name Glossolepis incisa or Glossolepis incisus?
The currently accepted name is Glossolepis incisa. The spelling Glossolepis incisus appears frequently in older aquarium literature and online references.

Is Red Rainbowfish the same as Salmon Red Rainbowfish?
Yes. Salmon Red Rainbowfish is another common name used for Glossolepis incisa.

How big does Red Rainbowfish get?
Adults commonly reach around 12 cm, with large mature males potentially approaching approximately 15 cm depending on genetics and conditions.

How many Red Rainbowfish should I keep?
Keep at least 6, with 8 or more preferred when space allows. They are social, active fish and generally look and behave better in a proper group.

Why is my Red Rainbowfish not red?
Young fish, females, stressed fish, and subordinate males may show little red colour. Mature confident males display the strongest red, and colour improves with age, good nutrition, stable water, and low stress.

Are female Red Rainbowfish red?
Not like adult males. Females are normally much more subtle, with olive, bronze, silver, or yellowish coloration.

What size tank does Red Rainbowfish need?
A 4-foot aquarium around 55 gallons or larger is a practical starting point for a proper adult group. Horizontal swimming space is especially important.

Can Red Rainbowfish live with Boesemani Rainbowfish?
Yes. They can make compatible tank mates when the aquarium is large enough for an active mixed rainbowfish group and all fish have sufficient swimming space and food access.

Is Red Rainbowfish aggressive?
It is generally peaceful, but very active. Its speed and adult size can intimidate extremely small, slow, or shy fish even when no true aggression is occurring.

What should I feed Red Rainbowfish for better colour?
Feed a varied diet including quality pellets, flakes, frozen brine shrimp, daphnia, krill-based foods, and some plant-based foods. Strong colour also depends heavily on genetics, sex, maturity, and overall health.