A highly active, schooling freshwater fish endemic to eastern Australia, often considered the original 'Australian Rainbowfish' in the aquarium trade. Recognizable by a prominent crimson red spot on the operculum (gill cover) and striking silvery-blue to greenish bodies. They are peaceful but extremely vigorous swimmers, requiring plenty of horizontal swimming space and a tight-fitting lid to prevent jumping.
Crimsonspotted Rainbowfish At a Glance
Crimsonspotted Rainbowfish Tank Requirements
Will Crimsonspotted Rainbowfish fit in your tank?
Care guides tell you what Crimsonspotted Rainbowfish needs, the next question is whether your tank can safely provide it. Test Crimsonspotted Rainbowfish against your tank size, maintenance needs, and the fish you already keep before you buy.
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Crimsonspotted Rainbowfish Water Parameters
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Crimsonspotted Rainbowfish Temperament & Compatibility
Crimsonspotted Rainbowfish Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Male
Males grow slightly larger and deeper-bodied than females. They feature intense coloration (especially during morning spawning displays) and possess elongated, pointed posterior rays on their dorsal and anal fins. Males may playfully spar or chase, so keeping a higher ratio of females is recommended to diffuse attention.
Differs in 1 trait from base species
Also known as: Show Male
Female
Females have a more slender, streamlined profile and distinctly rounded dorsal and anal fins. Their overall coloration is more subdued (typically pale silver, blue, or olive), though they still sport the characteristic crimson opercular spot. Essential for establishing a natural, stress-free shoal.
Differs in 1 trait from base species
Also known as: Female Rainbowfish, Subdued
Crimsonspotted Rainbowfish Care Guide Summary
The Crimsonspotted Rainbowfish, scientifically known as Melanotaenia duboulayi, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 12 cm and have a compressed 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 Crimsonspotted Rainbowfish requires a freshwater only aquarium with a minimum volume of 150 litres and a tank length of at least 90 cm. Water temperature should be maintained between 18°C and 28°C, with a pH range of 6.5–8 and a general hardness of 8–20 dGH. A moderate water flow is preferred.
The Crimsonspotted 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.
Crimsonspotted Rainbowfish Habitat Setup
When setting up an aquarium for the Crimsonspotted 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 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.
Crimsonspotted Rainbowfish Compatibility Notes
Classified as peaceful, the Crimsonspotted 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, 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.
Crimsonspotted Rainbowfish Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Crimsonspotted Rainbowfish.
40 Gallon Breeder
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
125 Gallon Standard
Show 9 more tank sizes
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Frequently Asked Questions About Crimsonspotted Rainbowfish
How big does Crimsonspotted Rainbowfish get?
Crimsonspotted Rainbowfish (Melanotaenia duboulayi) typically reaches a maximum adult size of approximately 12 cm. They have a compressed body shape and a moderate growth rate.
What tank size does Crimsonspotted Rainbowfish need?
A minimum aquarium volume of 150 litres and a tank length of at least 90 cm are recommended for Crimsonspotted Rainbowfish. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Crimsonspotted Rainbowfish need?
Crimsonspotted Rainbowfish thrives in freshwater only conditions with a temperature range of 18–28°C, a pH between 6.5 and 8, and a general hardness of 8–20 dGH. A moderate water flow is preferred.
Is Crimsonspotted Rainbowfish peaceful or aggressive?
Crimsonspotted 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 Crimsonspotted Rainbowfish should be kept together?
Crimsonspotted 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 Crimsonspotted Rainbowfish have any special tank requirements?
Yes. Crimsonspotted Rainbowfish benefits from plants - densely covered in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Crimsonspotted Rainbowfish need a lid on the tank?
Yes. Crimsonspotted 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 Crimsonspotted Rainbowfish
These fish are strong compatibility matches for Crimsonspotted Rainbowfish based on water preferences, temperament, adult size, and tank behavior.
Dainty Cory (Salt and Pepper Cory)
Corydoras habrosus
Ideal Tank MatesZebra Shovelnose (Tigrinus Catfish)
Brachyplatystoma tigrinum
Ideal Tank MatesIncolicana Corydoras
Corydoras incolicana
Ideal Tank MatesEmerald Green Cory
Corydoras splendens
Ideal Tank MatesDuplicareus Corydoras
Corydoras duplicareus
Ideal Tank MatesLoxozonus Corydoras (C079/C082)
Corydoras loxozonus
Ideal Tank MatesPlants That Suit Crimsonspotted Rainbowfish
These plants pair well with Crimsonspotted 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
Amazon Sword
Echinodorus amazonicus
Anacharis
Egeria densa
Anubias Barteri
Anubias barteri
Baby Tears
Lindernia rotundifolia
Balansae
Cryptocoryne crispatula
Fish Similar to Crimsonspotted Rainbowfish
Eastern Rainbowfish
Melanotaenia splendida
An active, schooling species native to Australia, highly variable in color depending on the catch location. They are fast swimmers that require long tanks with ample open swimming space. Because of their energetic feeding behavior, they can outcompete shy or slow-moving fish. Best kept in shoals to display natural morning sparring and courtship behaviors.
Exquisite Rainbowfish
Melanotaenia exquisita
A highly active, schooling species native to the fast-flowing, clear streams of Australia's Northern Territory. True to their name, they display stunning metallic bodies with bright red-tipped fins. They require pristine, well-oxygenated water, plenty of horizontal swimming space, and should always be kept in groups of 6 or more.
Banded Rainbowfish
Melanotaenia trifasciata
A large, robust, and highly active schooling fish native to Northern Australia. Famous for its intense geographic color variations (such as the red 'Goyder River' morph). They are peaceful but incredibly fast and vigorous swimmers, requiring long aquariums with plenty of open swimming space.
Turquoise Rainbowfish
Melanotaenia lacustris
A stunning, deep-bodied rainbowfish endemic to Lake Kutubu in Papua New Guinea. Famous for their ability to shift colors from deep teal to bright iridescent blue depending on mood and water quality. They are active schooling fish that thrive in hard, alkaline water.
Axelrod's Rainbowfish
Chilatherina axelrodi
A highly active, colorful schooling fish native to Papua New Guinea. Known for a bluish-grey upper body and yellowish-white lower body divided by a dark lateral stripe. Like most rainbowfish, they are incredibly fast, active swimmers that require pristine water, moderate flow, and significant horizontal swimming space.
Chequered Rainbowfish
Melanotaenia splendida inornata
An active, schooling rainbowfish native to the river systems of northern Australia. Named for the subtle iridescent, checkered pattern on their scales. They are highly energetic mid-water swimmers that require open horizontal swimming space combined with densely planted areas for security.