The anatomical structure of miniaturised cyprinids can vary greatly, and there are two principle ‘groupings’ with some species possessing intermediate features to some degree. The first contains those fishes which though small are essentially proportionally dwarfed versions of their larger relatives, e.g., Barboides, Microdevario, Microrasbora, Horadandia, Boraras, Sawbwa, Sundadanio, Danio, Laubuca and Rasbora.

The other includes those in which anatom…

In much of the literature this species is pictured with the invalid name R. paviei, due to an issue with spelling which was corrected by Kottelat (2005), and the common name 'sidestripe rasbora' although the latter has yet to find popularity in the aquarium hobby. There are a number of similar-looking species including R. sumatrana, R. hobelmani and R. laticlavia and it can be problematic to separate members of this 'group'. If the collection locality of the fish is known ide…

T. somphongsi is exceptionally rare both in nature and the hobby and was considered potentially extinct for around a dozen years before a trio were imported to Germany as contaminants among a batch of Boraras urophthalmoides in 2006.

Since then it has been successfully bred and distributed to various experts, mostly in Thailand and Germany, in the hope of establishing a sustainable captive population. The possibility of a…

The identity of this species was unclear for a number of decades prior to its redescription by Ng and Kottelat (2013).

The confusion originated with Brittan (1954) who misidentified specimens of R. tornieri as R. dusonensis and was exacerbated by Alfred (1963) who concluded that the holotype of R. dusonensis was conspecific with R. myersi.

It is unclear if this species has been available in the aquatic trade as collections from its native waters only occur sporadically, therefore we have based much of the information here on experience with its closest relative R. kalochroma. These two are almost identical in appearance and share some meristic features but R. kottelati possesses an additional, oval-shaped dark blotch on the caudal peduncle, lacks the stripe in the middle of the seen in R. kalochroma and is consequently easy to dis…

R. kalochroma exhibits variable patterning across its range according to locality with some forms possessing a line of spot-like markings connecting the two dark blotches on the flanks and others more intense body colouration. Juveniles are sometimes confused with Boraras maculatus and adults with the similarly-patterened R. elegans although the latter is easy to identify by its overall silver, as opposed to pinkish/reddish, colouration.

The only congener for which it may be genuinely mistake…

This fish may well be a form of R. dandia itself but in the absence of scientific confirmation we list it with a 'cf' abbreviation for the time being. It appears to be widely available in the trade but is often (mis)identified as R. wilpita, a species now confirmed as endemic to a small number of streams in Sri Lanka and which is probably much rarer in the hobby than previously thought.

Valenciennes initially described Leuciscus dandia as a new species from Sri Lanka in 1844 but the…

This species was described in 1999 and may still occasionally be seen on sale under the incorrect names R. reticulata or R. cf. reticulata as well as the trade name 'volcano rasbora'. The real reticulata is endemic to the small island of Nias which lies off Sumatra's northwestern coast and is virtually inaccessible to fish collectors so is unlikely to be in the hobby although it may have been exported on a couple of occasions. It's a deeper-bodied fish and does not exhibit th…

This species is rarely seen in the trade and little has been written regarding its captive care. It's possible that several colour forms may exist depending on collection locality.

Rainboth's 'Fishes of the Cambodian Mekong' characterised members of Rasbora by possession of an unbranched, non-spiny firstray and seven soft dorsal rays, origin of thein the middle of the body, five branchedrays, a small mouth not extending below the eye and a lack of barbels. It's long b…

This species was described from ‘Johore River, Segamat, Malaysia’, which corresponds to Segamat District within the the Johor River watershed, Johor state, southern Peninsular Malaysia, but the type specimens were obtained via a Singapore wholesaler so it’s possible that a mistake was made as there exist no other records of the species in Peninsular Malaysia.

It’s also been recorded from the Kapuas drainage…