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Maximum size : 12 cm

Omba Rainbowfish - Melanotaenia dumasi : Complete Fish Profile & Care Guide

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A large shoal of Omba Rainbowfish (Melanotaenia dumasi) creates a truly mesmerising spectacle within a spacious, well-planted aquarium. As they gracefully navigate through the lush vegetation, these vibrant fish become a living work of art. While the juveniles may initially appear less striking than their adult counterparts, their transformation within the secure confines of the planted aquarium is a remarkable sight to behold.

To fully appreciate the beauty and social dynamics of Omba Rainbowfish, it is recommended to maintain them in groups of six or more individuals of their own kind. The more individuals you can accommodate, the more enchanting their interactions become. An aquarium with a length of at least 4ft provides ample space for their lively movements. Heavy planting along the back and sides of the tank creates a natural habitat reminiscent of the dense vegetation found in their native environment. A well-designed layout should also incorporate an open swimming area in the centre, allowing these remarkable fish to showcase their elegance and agility.

Considering their preference for slightly alkaline water, providing conditions that emulate their natural habitat is ideal. However, Omba Rainbowfish are adaptable and can thrive in various water parameters. Regardless of the specific requirements, maintaining clean and well-filtered water is crucial for their overall well-being. It is worth noting that these fish have a remarkable ability to jump, making it essential to utilise tight-fitting cover slides to prevent accidental escapes.

In terms of temperament, Omba Rainbowfish are known for their peaceful nature. They coexist harmoniously with smaller tankmates, as their narrow mouths prevent them from preying on their companions. However, it is important to ensure that any potential tankmates are comfortable with the slightly higher temperatures these particular Rainbowfish prefer. By creating a suitable environment that addresses their social and environmental needs, you can fully appreciate the captivating beauty and graceful nature of the Omba Rainbowfish within your aquarium.

The adult male Omba Rainbowfish exhibits a stunning array of colours and patterns. Their bodies are predominantly greyish, often displaying a mesmerising coppery sheen along the back. As we move towards the anteroventral region, the colour transitions to a whitish hue, while the posteroventral area showcases a vibrant shade of blue. A distinctive narrow orange stripe runs between the horizontal scale rows on the upper side, adding a striking accent to their appearance.

One of the most eye-catching features of the male Omba Rainbowfish is the dark blue to blackish mid-lateral stripe that stretches from the eye to the base of the caudal fin. This stripe widens notably on the caudal peduncle, covering two horizontal scale rows. Immediately above and below this dark mid-lateral stripe, a vivid red-orange stripe enhances the overall allure of these magnificent fish. 

The upper portion of their head boasts a captivating blend of blue and brownish tones, while the lower half dazzles in a bluish-white shade. A silvery stripe extends behind the eye, gracefully crossing the upper cheek and middle of the operculum. This silvery stripe is often adorned with a small reddish spot towards the posterior end.

Regarding the fins, the Omba Rainbowfish presents a stunning display. The dorsal, anal, and caudal fins possess a translucent reddish hue, adding a touch of elegance to their appearance. The pelvic fins, on the other hand, shimmer in a white shade. The pectoral fins, being translucent, allow glimpses of the fish's intricate internal structures.

In the female Omba Rainbowfish, we observe a similar colour pattern to the males, albeit with slightly less vivid hues. In addition, the fins of the females are mainly translucent, lacking the reddish hue found in males. Despite these differences, males and females exhibit a remarkable beauty that will captivate any observer fortunate enough to witness their graceful presence.

Omba Rainbowfish Photos

Sexual Dimorphism

Distinguishing between male and female Omba Rainbowfish is relatively straightforward. Adult males exhibit distinct characteristics, being larger in size, possessing a deeper body structure, and displaying a more vibrant and striking colouration compared to females. In contrast, females tend to be smaller and have a less pronounced body shape and colouration.

Quick Facts

Scientific NameMelanotaenia dumasi
Year Described1907
Max Size12 cm
Aquarium LevelMiddle - Top
DifficultyBeginner - Intermediate
Best kept asGroups 6+
LifespanUp to 8 Years

Water Parameters

Water TypeFreshwater
PH7.0 - 8.0
GH8 - 10
77 - 82
25 - 28

Natural habitat

The Omba Rainbowfish is an intriguing species found exclusively in the captivating Omba River system of West Papua. This mesmerising aquatic habitat encompasses various waterways, including the Wa Udu River and the Wagani River, which are the primary outlet of the enchanting Lake Yamur. In these pristine waters, the Omba Rainbowfish thrives abundantly, particularly in the charming small creeks that gracefully merge into the majestic lake.

How to breed the Omba Rainbowfish

To successfully breed Omba Rainbowfish, it is recommended to establish a dedicated breeding aquarium with a substantial volume of mature tank water comprising 75% and 25% dechlorinated fresh water. In addition, introducing a small air-driven sponge filter will provide gentle circulation and filtration, maintaining optimal water conditions for the breeding process.

Maintaining a temperature of 28 °C is crucial to encourage successful breeding. A conditioned pair of Omba Rainbowfish should be carefully acclimated to the breeding aquarium, which should be adorned with an abundance of fine-leaved plants or clusters of Java moss. As the courtship begins, the male will entice the female by swimming in front of her, leading her over the plants and utilising the entire tank length. Gradually, the female will deposit eggs, scattering them over the plants in small batches.

It is essential to note that Omba Rainbowfish are considered "continual spawners," meaning that the spawning activity occurs over an extended period, ranging from several days to weeks or even months in some cases. This continuous spawning behaviour challenges aquarium enthusiasts, as some adult fish may consume the scattered eggs.

Many aquarists have successfully employed various techniques to mitigate this issue. For example, some prefer to siphon the eggs from the breeding tank into a separate aquarium containing water matching the conditions of the spawning tank. Alternatively, the use of spawning mops has proven effective. By carefully collecting many eggs on the mop, it can then be transferred to a separate tank with matching water parameters, while a fresh mop is introduced to allow the deposition of subsequent batches of eggs.

Under optimal conditions, the eggs typically hatch within 6 to 8 days, with the hatched fry becoming free-swimming. At this stage, providing an appropriate diet is crucial for their continued development. Infusoria serves as an excellent initial food source for the tiny fry, gradually transitioning to larger food items as they grow.

By employing these breeding strategies and maintaining suitable environmental conditions, aquarists can experience the joy of successfully breeding Omba Rainbowfish, contributing to the conservation of this captivating species.

Diet & feeding

Omba Rainbowfish possess an omnivorous nature foraging on various delicacies, including mosquito larvae, insects, small crustaceans, and zooplankton in the wild. Therefore, to ensure their optimal health and vibrant colouration, providing them with a protein-rich diet primarily composed of high-quality flakes and pellets is recommended.

Incorporating occasional live food into their feeding regimen is highly beneficial to accentuate their natural beauty. Offering live food options such as bloodworms, daphnia, and mosquito larvae two to three times weekly will bring out their full splendour. Feeding the Omba Rainbowfish three times daily while keeping portions small promotes their well-being. 

It is crucial to provide only the amount of food that can be consumed within three minutes, as these fish prefer surface feeding. Removing any uneaten food promptly prevents waste buildup and helps maintain optimal water conditions.

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