Dwarf Scissortail Rasbora - Rasbosoma spilocerca Fish Profile & Care Guide
Introduction
The Dwarf Scissortail Rasbora (Rasbosoma spilocerca) is an attractive freshwater fish native to the Mekong basin of Southeast Asia. This delicate species is naturally associated with shallow, clear waters where submerged grasses and fine-leaved aquatic plants provide shelter and feeding opportunities. Its slender body and distinctive dark markings on the fins give it an understated but elegant appearance, making it particularly appealing in carefully planted aquariums.
The Dwarf Scissortail Rasbora is a gentle, non-aggressive species, but its very small size and naturally cautious temperament mean it is not always well suited to a typical community aquarium. It is best kept either in a species-only setup or alongside other small, peaceful fish that are unlikely to intimidate or outcompete it. As a naturally social shoaling fish, it should be maintained in a group of at least 8–10 individuals, with larger groups being preferable where space allows.
Keeping a good number together helps the fish feel more secure, encourages natural behaviour and creates a much more attractive display within the aquarium. Males also tend to show stronger colouration when kept in a group, particularly when competing for the attention of females. Their interactions can add considerable interest to the aquarium without becoming aggressive or disruptive.
Dwarf Scissortail Rasboras are best kept in a mature, well-planted aquarium that offers plenty of shelter along with some open areas for swimming. Dense aquatic planting, especially fine-leaved and floating species, can help the fish feel secure and encourage more natural behaviour. Gentle filtration is preferable, as strong currents may cause unnecessary stress, while consistently clean and stable water conditions are particularly important for this delicate species. A natural-looking setup with subdued lighting, plant cover and darker areas within the aquarium can further enhance its sense of security and allow its subtle colouration and markings to stand out.
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Sexual Dimorphism
Sexual differences in Dwarf Scissortail Rasboras become more apparent as the fish mature. Males tend to have a slimmer, more streamlined body shape and generally display stronger, more vivid colouration, particularly when in breeding condition. Females are usually fuller-bodied, with a noticeably rounder abdomen that becomes more pronounced when carrying eggs. These differences are often subtle in younger fish but become easier to recognise in healthy, mature specimens.
Quick Facts
| Scientific Name | Rasbosoma spilocerca |
|---|---|
| Year Described | 2010 |
| Kingdom | Animalia |
| Classification | Actinopterygii |
| Order | Cypriniformes |
| Family | Danionidae |
| Genus | Rasbosoma |
| Origins | Cambodia Thailand Laos |
| Approx Max Size | 3 cm |
| Temperament | Peaceful |
| Aquarium Level | Middle - Top |
| Difficulty | Intermediate |
| Shoaling | Yes |
| Best kept as | Groups 8+ |
| Diet & Feeding | Omnivore |
| Reproduction | Egg-Scatterer |
| Average Lifespan | Up to 5 Years |
Water Parameters
| Water Type | Freshwater |
|---|---|
| pH | 6.0 - 7.0 |
| GH | 2 - 10 |
| KH | 1 - 5 |
| TDS | 50 - 180 |
| ℉ | 73 - 79 |
|---|---|
| ℃ | 22 - 26 |
Natural Habitat
The Dwarf Scissortail Rasbora is native to the Mekong Basin of Southeast Asia, where it occurs in Cambodia, Laos and Thailand. Throughout its range, the species is closely associated with shallow freshwater habitats such as marshes, swamps, floodplains and seasonally inundated fields. It is particularly characteristic of clear, relatively calm waters containing dense beds of submerged grasses and fine-leaved aquatic plants, where it commonly occupies the upper layers of the water. Seasonal flooding allows it to move into newly inundated areas during periods of high water, taking advantage of the temporary wetland habitat. Although it may occasionally occur in flowing waterways, it is primarily a species of slow-moving or still, heavily vegetated environments.
Breeding
The Dwarf Scissortail Rasbora is an egg-scattering species that may spawn regularly when adults are healthy and maintained in suitable conditions. During spawning, eggs are released among fine-leaved plants and other dense vegetation rather than being placed in a prepared nest. The adults provide no care for either the eggs or developing young and may consume them if given the opportunity, so dense planting can greatly improve the chances of fry surviving. Newly hatched fry are extremely small and initially require microscopic foods before gradually progressing to larger live foods as they develop.
Diet & Feeding
The Dwarf Scissortail Rasbora is primarily a micropredator, naturally feeding on zooplankton, small insects and other tiny aquatic organisms. In the aquarium, it should be offered suitably small foods that can be easily taken by its small mouth. High-quality prepared foods can form part of the diet, but regular offerings of small live or frozen foods such as Daphnia, Artemia and similar invertebrates are beneficial. Providing a varied diet helps maintain good condition, encourages natural feeding behaviour and can promote stronger colouration.
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Published: 13 Aug 2026
Last Updated: 13 Aug 2026