Melanotaenia Fasinensis Rainbowfish: A Comprehensive Care Guide
The Fasinensis Rainbowfish (Melanotaenia fasinensis) is a lesser-known but attractive species of rainbowfish native to Papua New Guinea. Like many members of the Melanotaenia genus, this species is valued for its shimmering body coloration and active schooling behavior. When kept in groups and provided with excellent water quality, males can develop beautiful metallic colors that shift between blue, green, and yellow tones depending on lighting and mood.
Although not as widely available in the aquarium trade as species like Boesemani or Praecox rainbowfish, Fasinensis Rainbowfish are hardy, peaceful fish that adapt well to planted community aquariums. Their active nature and vibrant coloration make them a rewarding species for aquarists interested in keeping more uncommon rainbowfish.
Natural Habitat and Distribution
Fasinensis Rainbowfish are native to Papua New Guinea, where they inhabit freshwater rivers and streams within the region.
In the wild they are typically found in:
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Slow to moderately flowing streams
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Clear freshwater rivers
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Areas with submerged vegetation
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Shoreline zones with open swimming space
These environments usually feature warm water, moderate current, and plenty of plant cover.
Size
Adult size: approximately 4 inches (10 cm)
Males typically grow slightly larger than females and develop deeper bodies with more vibrant coloration as they mature.
Tank Size
Minimum tank size: 40 gallons
Recommended tank size: 55 gallons or larger
Fasinensis Rainbowfish are active swimmers and should be kept in groups of at least 6 fish. A longer aquarium is ideal because it provides space for schooling and natural swimming behavior.
Water Parameters
Fasinensis Rainbowfish are adaptable but prefer stable water conditions.
Temperature: 75–82°F
pH: 6.5–7.8
Hardness: soft to moderately hard
Regular water changes and good filtration help maintain the clean water conditions these fish prefer.
Aquarium Setup
A planted aquarium works very well for Fasinensis Rainbowfish.
Recommended tank features include:
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Live plants along the sides and back of the aquarium
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Open swimming areas in the center
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Driftwood or rock structures
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Moderate water flow
Like many rainbowfish species, they appreciate a combination of dense plant cover and open swimming space.
Diet
Fasinensis Rainbowfish are omnivorous and accept a wide range of foods.
In the aquarium they will eat:
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High-quality flakes
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Small pellets
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Frozen foods such as brine shrimp or bloodworms
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Live foods when available
Providing a varied diet helps maintain their health and encourages stronger coloration.
Behavior and Temperament
Fasinensis Rainbowfish are peaceful schooling fish that spend most of their time swimming in the middle and upper areas of the aquarium.
Typical behaviors include:
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Active midwater swimming
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Males displaying to one another
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Peaceful interactions with other fish
Keeping multiple males often results in more vibrant color displays.
Tank Mates
Because of their peaceful nature, Fasinensis Rainbowfish do well in community aquariums.
Good tank mates include:
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Tetras
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Rasboras
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Corydoras
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Peaceful dwarf cichlids
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Other rainbowfish species
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Peaceful gouramis
Avoid aggressive fish or species that may nip fins.
Breeding
Like most rainbowfish, Fasinensis Rainbowfish are egg-scattering spawners.
Breeding characteristics include:
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Eggs are deposited among fine-leaved plants or spawning mops
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Spawning often occurs early in the morning
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Adults do not guard the eggs and may eat them
Fry can initially be fed infusoria before moving to baby brine shrimp as they grow.
Fun Facts
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Fasinensis Rainbowfish belong to the diverse Melanotaenia genus, which includes many of the most popular rainbowfish species in the aquarium hobby.
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Mature males often develop stronger coloration and deeper bodies when kept in groups with other males.
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Like many rainbowfish, this species displays its best colors when provided with high-quality food and excellent water conditions.
Conclusion
The Fasinensis Rainbowfish is a peaceful and attractive species that can make a great addition to larger community aquariums. While not as commonly seen as some other rainbowfish, its shimmering colors and active schooling behavior make it a rewarding fish to keep. With proper care, stable water conditions, and a well-planted aquarium, Fasinensis Rainbowfish can thrive and become a beautiful highlight in a freshwater tank.
Looking to Add Fish to Your Aquarium?
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