Sabah Rasbora - Rasbora rheophila Fish Profile & Care Guide
Introduction
The Sabah Rasbora is a peaceful, shoaling fish that thrives when kept in groups. It displays more natural behaviour and vibrant colours when surrounded by its own kind. A minimum group of six individuals is recommended, though larger shoals of ten or more are ideal. Shoaling provides a sense of security, helps reduce stress, and brings out more dynamic interactions within the group.
Regarding tankmates, Sabah Rasbora is best kept with other small, non-aggressive species that enjoy similar water conditions. Suitable companions include other peaceful cyprinids (like smaller Boraras species), small Tetras, Danios, and bottom-dwellers such as Corydoras Catfish or small Loaches. Shrimp and other invertebrates are also usually safe, provided the Rasboras are well-fed, and the shrimp aren't tiny enough to be seen as food.
The aquarium should be well-filtered with moderate to strong water movement to simulate its natural environment, as this species comes from flowing waters. An aquarium of at least 60 litres (around 15 gallons) is suitable for a small group, with plenty of open swimming space. Subdued lighting and a soft, sandy or fine gravel substrate are ideal. Adding driftwood, rocks, and dense planting can provide cover and reduce stress, but be sure to leave open areas for swimming. Clean, well-oxygenated water is essential, and regular maintenance is vital to keep nitrate levels low. Rasbora rheophila is sensitive to poor water quality, so weekly water changes and good filtration are key to its long-term health.
Sabah Rasbora is easy to tell apart from other Rasboras. It has a slim body, a rounded snout, and a dorsal fin that sits further back than most. Its back is olive-coloured, while the sides are silvery-grey with a dark stripe that runs from the head to the base of the tail. The tail fin usually has a grey to black edge, though in some groups, this colouring only appears on the upper part of the tail.
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Photos
Sexual Dimorphism
Sexual dimorphism in Sabah Rasboras is subtle but can be observed closely, particularly when the fish are mature and in good condition. Males tend to be more slender and slightly smaller than females. They often display more vivid colouration, especially during courtship or when competing for the attention of females. The dark lateral stripe running along the body may appear more pronounced in males, and the fins, particularly the caudal fin, can sometimes take on deeper shades of grey or black near the edges. Females, on the other hand, are generally fuller-bodied, particularly when carrying eggs. This rounder appearance is especially noticeable in the belly area. Their colouration tends to be slightly duller or less intense than the males, although environmental conditions and health can influence this.
Quick Facts
| Scientific Name | Rasbora rheophila |
|---|---|
| Year Described | 2012 |
| Kingdom | Animalia |
| Classification | Actinopterygii |
| Order | Cypriniformes |
| Family | Danionidae |
| Genus | Rasbora |
| Origins | Malaysia |
| Approx Max Size | 6 cm |
| Temperament | Peaceful |
| Aquarium Level | Middle - Top |
| Difficulty | Beginner - Intermediate |
| Shoaling | Yes |
| Best kept as | Groups 6+ |
| Diet & Feeding | Omnivore |
| Reproduction | Egg-Scatterer |
| Average Lifespan | Up to 5 Years |
Water Parameters
| Water Type | Freshwater |
|---|---|
| pH | 6.0 - 7.5 |
| GH | 2 - 12 |
| ℉ | 72 - 79 |
|---|---|
| ℃ | 22 - 26 |
Natural Habitat
The Sabah Rasbora is a freshwater species found exclusively in Sungai Pangakatan, a tributary of the Sungai Liwagu in Sabah, northern Borneo (Malaysia). These fish are native to steep, high-gradient mountain streams, where they inhabit large, deep pools partially isolated from the main flow and influenced by counter-currents.
Their natural environment is characterised by crystal-clear, fast-moving water with a substrate of sand or rock, often scattered with leaf litter and submerged roots. The water is usually soft and slightly acidic, providing ideal conditions for foraging and spawning. These stable, oxygen-rich habitats are crucial for their survival.
However, ongoing threats from logging, agriculture, and urban expansion in the region are putting pressure on their native habitats. As a result, Sabah Rasboras remains uncommon in the aquarium trade, and wild-caught specimens are rarely available. Their restricted range and specialised habitat make them one of the less frequently seen members of the Rasbora genus in the hobby.
Breeding
Breeding Sabah Rasboras in captivity is possible but requires carefully managed conditions to mimic their natural spawning environment. Like most Rasboras, they are egg-scattering spawners and do not exhibit any parental care. In the wild, spawning typically occurs in shallow, flowing waters over leaf litter or fine substrates, especially after seasonal rainfall when water conditions shift.
To encourage breeding in the aquarium, it's best to set up a separate spawning tank with soft, slightly acidic water, a suitable temperature and gentle filtration such as a sponge filter. A thin layer of fine-leaved plants like Java moss or spawning mops should be added to provide a place for eggs to settle. The water should be very clean, with low hardness and minimal nitrates.
Conditioning the adults with a high-quality diet of frozen or live foods such as daphnia, mosquito larvae, or brine shrimp can help trigger spawning behaviour. When ready, the males chase females and display enhanced colours, especially along their lateral stripe and fins. Spawning usually occurs in the early morning, with eggs scattered randomly among plants or over the substrate.
Once eggs are laid, it's crucial to promptly remove the adults, as they may eat them. The eggs, though tiny and translucent, are the future of sustainable aquarium populations. Depending on temperature, they hatch within 24 to 36 hours, and the fry becomes free-swimming after 3 to 5 days. These young fish initially require microscopic food such as infusoria or commercial liquid fry food, followed by baby brine shrimp as they grow. Successful breeding of Sabah Rasboras can significantly contribute to sustainable aquarium populations and reduce the pressure on wild-caught specimens, making it a rewarding and responsible endeavour for hobbyists.
Diet & Feeding
The Sabah Rasbora is an omnivorous species with a diet primarily consisting of small aquatic invertebrates and organic matter in the wild. In their natural habitat, these fish feed on tiny insects, crustaceans, zooplankton, and other microfauna that drift in the current, as well as some algae and plant debris. In the aquarium, Sabah Rasboras readily accepts a variety of prepared and live foods. A balanced diet should include high-quality micro or nano-sized flake foods or pellets formulated for small tropical fish. To support optimal health, colouration, and breeding conditions, their diet should be supplemented regularly with live or frozen foods, like daphnia, baby brine shrimp, bloodworms, and mosquito larvae. These protein-rich options closely mimic the drifting prey they consume in the wild and help stimulate natural foraging behaviour.
Other Rasboras
Published: 26 Mar 2025
Last Updated: 26 Mar 2025