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Family: Cyprinidae, Subfamily Danioninae

Common Name: Mosquito Rasbora

Origin and Habitat: Endemic to southwestern Borneo, Indonesia. Occurs in dimly-lit and slow-moving quiet blackwater streams and ponds in forest peat swamps.

Compatibility/Temperament: Very peaceful, must be kept in a group of at least six but preferably nine or more. Given its small size it is best in smaller tanks as a group or with similar quiet fish such as the Trigonstigma rasbora species, dwarf cory species, dwarf loach species, Dario dario, etc. Best not kept with other species in the genus as they will likely cross-breed. Tends to be "lost" in larger aquaria.

Mosquito Rasbora Diet

Feeds on insects, small crustaceans and zoo-plankton in nature; readily accepts prepared foods, with frozen daphnia and brine shrimp ideal.


Just over 1 inch (3 cm).

Minimum Tank Suggestion

5 gallons.

Water parameters for Mosquito Rasbora

Very soft (hardness < 10 dGH) acidic (pH below 7) water, temperature 25-28C/77-82F.


This is the most commonly seen of the present six species in this genus of miniature rasbora fishes, all of which are very similar not only in colouration and patterning but also in their requirements and behaviours. It is recommended that the species not be mixed in the same aquarium as they may cross-breed.

This beautiful little fish will be at its most colourful in a group in a dimly lit and well planted aquarium containing some driftwood. As little water current as possible will suit it admirably; floating plants are mandatory. This fish tends to remain in a group as they explore the plants and every area of the aquarium in search of microscopic food.

Females are rounder than males, and males are more colourful especially when displaying. This fish is an egg-scatter and a continuous spawner, meaning that with a group of males and females in the right environment [an established and mature well-planted tank with soft, acidic water] a few eggs will be laid daily, and some of the fry will likely survive with no intervention from the aquarist.

The common name "Mosquito Rasbora" is a translation of the German common name given to this fish by its discovers; the collection site was heavily infested with mosquito, hindering collection.

The species was originally described by D. Vogt (1978) as Rasbora urophthalma brigittae, thus a subspecies of B. urophthalma. The epithet urophthalma derives from the ancient Greek oura [=tail] and ophthalmos [=eye], referring to the tail spot, and brigittae honours Vogt's wife, Brigitte. In 1993, Kottelat & Vidthayanon erected the new genus Boraras for the (new) type species B. micros on the basis of morphology and reproduction methods, and also moved the four small-bodied Rasbora species into this genus, raising the subject fish to distinct species status as B. brigittae. A sixth species has now been described (Conway & Kottelat, 2011). The name Boraras is an anagram of "Rasbora" referring to the reverse ratio of abdominal and caudal vertebrae in Boraras compared to Rasbora.

All six species in this genus have a distinctive colouration and patterning. On a reddish background, in B. maculatus, B. micros and B. naevus there are three roundish black/dark brown blotches, one being a shoulder patch that is larger than the eye, a second at the origin of the anal fin, and the third on the caudal peduncle (at the base of the caudal fin). On B. brigittae and B. urophthalmoides there is a black/dark brown midlateral stripe and the caudal fin base blotch, and on B. merah there is an elongated blotch of the same colour on the anterior third of the body and then a much narrower midlateral line leading to the caudal fin base (Conway & Kottelat, 2011).

In the first phylogenetic analysis of the species in Boraras, Conway (2005) established the monophyletic lineage of this genus. Dr. Conway noted that the interrelationships of the five Boraras species remains unresolved, and no evidence was found to suggest that Boraras and Trigonostigma are closely related.

Very recent work by Tang, et al (2010) has clarified the phylogeny of the genera in the monophyletic subfamily Danioninae that includes the species within Rasbora, Boraras and Trigonostigma. Monophyletic means that all species are descended from a single common ancestor included within that clade.


Conway, Kevin W. (2005), "Monophyly of the genus Boraras (Teleostei: Cyprinidae)," Ichthyological Exploration of Freshwaters, Vol. 16, No. 3, pp. 249-264.

Conway, Kevin W. and Maurice Kottelat (2011), "Boraras naevus, a new species of miniature and sexually dichromatic freshwater fish from peninsular Thailand (Ostariophysi: Cyprinidae)," Zootaxa, Vol. 3002, pp. 45-51.

Kottelat, Maurice and C. Vidthayanon (1993), "Boraras micros, a new genus and species of minute freshwater fish from Thailand (Teleostei: Cyprinidae)," Ichthyological Exploration of Freshwaters, volume 4 (no. 2), pp. 161-176.

Tang, K.L., M.K. Agnew, M.V. Hirt, T. Sado, L.M. Schneider, J. Freyhof, Z. Sulaiman, E. Swartz, C. Vidthayanon, M. Miya, K. Saitoh, A.M. Simons, R.W. Wood and R.L. Mayden (2010), "Systematics of the subfamily Danioninae (Teleostei: Cypriniformes: Cyprinidae)," Molecular Phylogenetics and Evolution, volume 57, pp. 189-214.

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