A brilliantly colored, peaceful dwarf rainbowfish native to the upper Fly River system in Papua New Guinea. Recognized by its golden-turquoise sheen, distinctive horizontal stripes, and sometimes bright pink lips. Being an exceptionally active shoaling species, they require significant lateral swimming space despite their small size.
Fly River Rainbowfish At a Glance
Fly River Rainbowfish Tank Requirements
Will Fly River Rainbowfish fit in your tank?
Care guides tell you what Fly River Rainbowfish needs, the next question is whether your tank can safely provide it. Test Fly River Rainbowfish against your tank size, maintenance needs, and the fish you already keep before you buy.
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Fly River Rainbowfish Water Parameters
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Fly River Rainbowfish Temperament & Compatibility
Fly River Rainbowfish Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Male
Males develop deeper bodies, brighter golden-turquoise coloration, and more elaborate finnage as they mature. During morning spawning displays, males will 'flash' an intense, neon courtship stripe along their nape and exhibit highly energetic behavior.
Differs in 2 traits from base species
Also known as: Show Male
Female
Females are slightly smaller, more slender, and noticeably less colorful than males, typically maintaining a more subdued silvery-yellow hue. Keeping a proper ratio of females is essential for keeping males relaxed and encouraging their best displays.
Differs in 2 traits from base species
Also known as: Unsexed, Juvenile
Fly River Rainbowfish Care Guide Summary
The Fly River Rainbowfish, scientifically known as Melanotaenia sexlineata, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 7.5 cm and have a fusiform body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the surface and mid-level zones of the aquarium and produces a low level of biological waste.
To thrive, the Fly River Rainbowfish requires a freshwater only aquarium with a minimum volume of 110 litres and a tank length of at least 90 cm. Water temperature should be maintained between 24°C and 28°C, with a pH range of 6–7.5 and a general hardness of 4–15 dGH. A moderate water flow is preferred.
The Fly River Rainbowfish is a rewarding species to keep, provided its core environmental needs are met. This species is available in 2 varieties: Male and Female. Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Fly River Rainbowfish Habitat Setup
When setting up an aquarium for the Fly River Rainbowfish, a moderate water flow best suits their natural preferences. Because this species occupies the surface and mid-level zones, the aquarium layout should prioritise adequate surface area with floating cover to make them feel secure near the waterline and open swimming space in the centre of the tank for free movement. Useful additions include light plant coverage for partial shade and dense planting to provide cover, break sightlines, and reduce stress. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Fly River Rainbowfish Compatibility Notes
Classified as peaceful, the Fly River Rainbowfish is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. When choosing tankmates, shy or slow-feeding tankmates may be outcompeted at feeding time and their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the surface and mid-level zones can help reduce competition and territorial overlap.
Fly River Rainbowfish Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Fly River Rainbowfish.
30 Gallon Breeder
40 Gallon Breeder
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
Show 10 more tank sizes
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Frequently Asked Questions About Fly River Rainbowfish
How big does Fly River Rainbowfish get?
Fly River Rainbowfish (Melanotaenia sexlineata) typically reaches a maximum adult size of approximately 7.5 cm. They have a fusiform body shape and a moderate growth rate.
What tank size does Fly River Rainbowfish need?
A minimum aquarium volume of 110 litres and a tank length of at least 90 cm are recommended for Fly River Rainbowfish. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Fly River Rainbowfish need?
Fly River Rainbowfish thrives in freshwater only conditions with a temperature range of 24–28°C, a pH between 6 and 7.5, and a general hardness of 4–15 dGH. A moderate water flow is preferred.
Is Fly River Rainbowfish peaceful or aggressive?
Fly River Rainbowfish is classified as peaceful with an aggression score of 2 out of 10. They are generally well-suited to peaceful community tanks.
How many Fly River Rainbowfish should be kept together?
Fly River Rainbowfish is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.
Does Fly River Rainbowfish have any special tank requirements?
Yes. Fly River Rainbowfish benefits from plants - densely covered and plants - lighly covered in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Fly River Rainbowfish need a lid on the tank?
Yes. Fly River Rainbowfish is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.
Top Tank Mates for Fly River Rainbowfish
These fish are strong compatibility matches for Fly River Rainbowfish based on water preferences, temperament, adult size, and tank behavior.
Mottled Loach
Paracanthocobitis botia
Ideal Tank MatesSchwartz's Cory
Corydoras schwartzi
Ideal Tank MatesLeopard Cory
Corydoras leopardus
Ideal Tank MatesGold Laser Cory
Corydoras sp. 'CW010'
Ideal Tank MatesDainty Cory (Salt and Pepper Cory)
Corydoras habrosus
Ideal Tank MatesZebra Shovelnose (Tigrinus Catfish)
Brachyplatystoma tigrinum
Ideal Tank MatesPlants That Suit Fly River Rainbowfish
These plants pair well with Fly River Rainbowfish based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
Afzel's Anubias
Anubias afzelii
Anacharis
Egeria densa
Baby Tears
Lindernia rotundifolia
Balansae
Cryptocoryne crispatula
Bog Moss
Mayaca fluviatilis
Bonsai Rotala
Rotala indica
Fish Similar to Fly River Rainbowfish
MacCulloch's Rainbowfish (Dwarf Rainbowfish)
Melanotaenia maccullochi
A smaller, peaceful species of rainbowfish native to Australia and Papua New Guinea. They feature striking silver/yellow bodies with horizontal red, brown, or orange stripes. Unlike larger Melanotaenia species, their smaller size makes them suitable for medium aquariums. They are highly active schooling fish that require open swimming space and display their best colors in the morning.
New Guinea Rainbowfish
Melanotaenia affinis
An active, schooling species native to the streams of northern New Guinea. Known for their striking lateral stripe and vibrant fin coloration that flashes during morning displays. They are peaceful but highly energetic, requiring ample open swimming space and highly oxygenated water to thrive.
Allen's Rainbowfish
Chilatherina alleni
A rare and highly active rainbowfish native to West Papua, Indonesia (Wapoga River basin). Known as the 'Wapoga Rainbowfish', they undergo a dramatic color transformation as they mature, developing intense metallic blues, greens, and reds. As exceptionally fast, continuous swimmers, they require a 4-foot (120cm) aquarium minimum to thrive without stress.
Blue Rainbowfish
Melanotaenia caerulea
A small, highly active, and colorful schooling fish native to the Kikori River system in Papua New Guinea. They are peaceful but require ample swimming space and a school of their own kind to thrive. Like most rainbowfish, they appreciate well-oxygenated, flowing water and are excellent jumpers. Males develop a striking blue hue with reddish horizontal stripes.
Goldie River Rainbowfish
Melanotaenia goldiei
The Goldie River Rainbowfish is a vibrant, highly active schooling fish native to the clear rainforest streams and backwaters of southern New Guinea. As rapid swimmers, they require significant open swimming space. They are voracious mid-water and surface feeders that will readily eat insects and standard aquarium foods. While peaceful, their exuberant energy can intimidate shy tank mates.
Leggett's Rainbowfish
Glossolepis leggetti
A rare and highly active schooling fish native to the Wapoga and Tiawiwa River systems in West Papua, Indonesia. Known for its distinct sexual dimorphism as it matures, with males developing a deep arch and striking green/blue iridescence. Like most rainbowfish, they require highly oxygenated water, moderate flow, and significant horizontal swimming space.