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Maximum size : 10 cm

Murray River Rainbowfish - Melanotaenia fluviatilis : Complete Fish Profile & Care Guide

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Experience the captivating beauty of the Murray River Rainbowfish (Melanotaenia fluviatilis), a remarkable aquatic gem that brings tranquillity to your aquarium. While less widely seen in the hobby than some of its relatives, dedicated enthusiasts can still discover these elegant fish. Ideally suited for novice fish keepers, they possess a gentle nature that creates a harmonious environment.

Adaptable to varying temperatures and water conditions, Murray River Rainbowfish showcase their remarkable hardiness by fending off the most common diseases. However, in the rare event that medical intervention is required, they respond favourably to appropriate treatments. Furthermore, breeding these magnificent creatures is a breeze, adding to the appeal of incorporating them into your aquatic haven.

Watch in awe as the Murray River Rainbowfish gracefully glide through the water, their swift movements adding an element of excitement to your tank. While their larger size and sudden motions may disturb smaller or slower fish, they harmonise splendidly with similarly-sized Rainbowfish, Barbs, Danios, Tetras, and Corydoras Catfish.

These lively creatures thrive best when kept in groups of six to eight individuals, ideally more. Ensuring a balanced mix of genders promotes harmony among them, resulting in enhanced colouration and vibrant displays. Witness the males flaunting their finest hues in the company of their peers, creating a mesmerising spectacle. So naturally, a suitably-sized aquarium is necessary to accommodate a considerable group of these enchanting fish.

Create a planted aquarium for an authentic natural setting where the Murray River Rainbowfish can flourish. Combining dense vegetation with open spaces for unrestricted swimming creates an environment reminiscent of their native habitat. While other decorations are of secondary importance, selecting plants that mirror their preference for slightly hard, alkaline conditions is crucial. Employ efficient filtration and diligent tank maintenance to encourage the male fish to develop their stunning colouration, ensuring they truly shine.

Behold the exquisite features of the Murray River Rainbowfish, boasting elongated bodies, small heads, and captivating large eyes. A shallowly forked caudal fin complements its two dorsal fins and pointed anal fin. With fins adorned in yellow hues, highlighted by dark margins and adorned with gorgeous orange or red markings, they radiate elegance.

Intriguingly, the Murray River Rainbowfish display a shimmering silvery-brown colouration on their sides, accentuating a radiant green or silver sheen. In addition, a mesmerising blue stripe gracefully extends from their snout to the caudal fin, further adding to their allure. Meanwhile, their remaining fins, embellished with orange or red patterns, exhibit a striking yellow tone.

Within the male specimens, vibrant orange stripes run laterally across the posterior half of their bodies, culminating in stunning red spots on their dorsal, anal, and caudal fins, accompanied by a captivating blackish margin during breeding. Females, while still charming, exhibit slightly subdued colouring, lacking some of the brilliance and red stripes along the caudal peduncle.

Murray River Rainbowfish Photos

Sexual Dimorphism

Sexual dimorphism is evident within the Murray River Rainbowfish species, with distinct differences between males and females. Typically, the males exhibit a larger and more robust body structure compared to their female counterparts. 

A notable characteristic of mature males is the elongation of the posterior rays in both the second dorsal and anal fin, setting them apart. Moreover, these vibrant males boast more vivid and striking colouration, further accentuating their visual appeal.

On the other hand, females can be identified by their smaller and rounded dorsal and anal fins, distinguishing them from males. This disparity in fin morphology adds to the observable distinctions between the sexes, reflecting the intricate biological variations within the species.

Quick Facts

Scientific NameMelanotaenia fluviatilis
Year Described1878
Other NamesAustralian Rainbowfish
Max Size10 cm
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 6+
LifespanUp to 8 Years

Water Parameters

Water TypeFreshwater
PH6.5 - 8.5
GH8 - 25
68 - 77
20 - 25

Natural habitat

Journey to the captivating freshwater systems of southeastern Australia, where the Murray River Rainbowfish proudly calls home. These remarkable species thrive in the pristine waters west of the Great Dividing Range, particularly within the magnificent Murray-Darling Basin of New South Wales and southern Queensland. However, the splendour of their presence extends to the Campaspe River and Goulburn River in Victoria, representing the southernmost reaches of their distribution.

Immerse yourself in the diverse habitats that these enchanting Rainbowfish inhabit. They gracefully gather in schools within the tranquil embrace of slow-flowing rivers, serene wetlands, and beautiful billabongs. Yet, their adaptability knows no bounds, as they also venture forth to colonise rivers, creeks, drains, ponds, reservoirs, and even occasional stagnant waterholes. 

Uniquely suited to their southernmost range, the Murray River Rainbowfish demonstrates unparalleled resilience, braving the relatively low winter temperatures ranging from 10 to 15 °C that prevail in the middle and lower reaches of the mighty Murray River.

How to breed the Murray River Rainbowfish

The Murray River Rainbowfish exhibits a distinct and well-regulated reproductive cycle, characterised by spawning activities typically transpiring between October and January, coinciding with rising water temperatures. In controlled environments, spawning can occur year-round when maintaining temperatures above 20°C. 

Remarkably, females have the capacity to produce between 100 and 150 eggs, engaging in multiple spawning events daily over several days. This natural phenomenon primarily occurs in the early morning or evening, just before the onset of darkness.

During the spawning process, each female releases a succession of eggs, subsequently fertilised by the male. These eggs possess a spherical shape and a colourless appearance, affixing themselves to delicate-leaved aquatic plants or entwining among the roots of floating vegetation with the assistance of numerous long and slender filaments originating from a single point on the egg membrane.

The eggs hatch within 5 to 9 days after fertilisation, contingent upon water temperatures ranging between 24 and 29°C. The incubation period exhibits a temperature-dependent relationship, as higher temperatures expedite the hatching process. It is important to note that eggs incubated at temperatures below 20°C may not successfully hatch, reducing overall fertility.

Upon hatching, the newly emerged larvae rapidly absorb the yolk sac within 3 to 5 days. These delicate beings swiftly ascend to occupy the uppermost layer of the water, specifically within the upper centimetre, and commence feeding within a mere 24 hours after birth. Furthermore, developing their swim bladder is a remarkable feat, achieving inflation a mere 10 hours post-hatching.

The growth rate of these vibrant juveniles exhibits notable variations, subject to a multitude of factors, including temperature differentials, feeding frequency, and population densities. Nonetheless, it is noteworthy that the Murray River Rainbowfish demonstrates remarkable growth during its juvenile stage, reaching maturity within the year following its initial hatching, showcasing its remarkable resilience and vitality.

Diet & feeding

The dietary preferences of the esteemed Murray River Rainbowfish encompass a diverse array of food sources, rendering them an omnivorous species. However, their natural inclination leans towards consuming aquatic invertebrates and terrestrial arthropods that find their way into the water. Hence, a meticulously planned diet is imperative to ensure optimal health and vibrant colouration in captivity.

To meet these remarkable fish's nutritional requirements, approximately 60 to 75% of their diet is recommended to comprise high-quality processed food specially formulated for fish of their size. This serves as a crucial foundation for their well-being. Complementing this processed food, the remaining portion of their diet should consist of live foods. Among the viable options are white worms, blood worms, and brine shrimp, all of which provide essential nutrients. 

In situations where these live food sources are unavailable, suitable frozen alternatives can be utilised without compromising their nutritional needs.

To establish a healthy feeding routine, offering meals to the Murray River Rainbowfish 2 to 3 times a day is advised. However, providing them with a quantity of food that can be consumed within fewer than 5 minutes is essential. This feeding regimen ensures they receive an adequate and balanced diet, promoting their overall well-being while preventing excessive food waste.

With a well-planned and nutrient-rich diet, you can delight in the vibrant health and colouration displayed by the extraordinary Murray River Rainbowfish, showcasing the pinnacle of their potential within the confines of captivity.

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