Brevibora dorsiocellata - Eyespot Rasbora

Cyprinidae

Native to southern Peninsular Malaysia and the Greater Sunda islands of Borneo and Sumatra. In Peninsular Malaysia localities include the Selai and Muar rivers in Johor state and the blackwater swamp lake of Tasek Bera in Pahang state while in Sumatra the only report we've been able to find seems to refer to the Lalah River, Riau province in the east of the island.

Records from Borneo are confusing. It seems to be restricted to southern (Indonesian) parts of the island and has been recorded from various rivers and streams within the lower Kapuas River basin and the Ketungau river in West Kalimantan (Kalimantan Barat) province as well as tributaries of the Sebangau and lower Mentaya rivers in Central Kalimantan (Kalimantan Tengah). However it's possible that some or even all of the records from the Kapuas may actually refer to Rasbora macrophthalma. Until a scientific comparison between the forms of the species from the islands and mainland is conducted it is unlikely that the truth will reveal itself. In any case wild caught fish are quite rare in the hobby as the species is being produced commercially in several countries.

Mostly inhabits gently flowing black water streams and rivers associated with ancient forest peat swamps. The water is stained brown due to the release of tannins and other chemicals released by decomposing organic matter and the substrate scattered with fallen leaves, twigs and branches. Such environments characteristically contain very soft (negligible hardness), acidic (pH as low as 4.0) water and are often dimly-lit due to the forest canopy above. Across much of Southeast Asia these biotopes are under threat from rubber/palm oil plantations, building developments and other human activities.

Around 1.4"/3.5cm.

A group will need a tank measuring a minimum of 18" x 12" x 12"/45cm x 30cm x 30cm/42.5 litres.

Choice of décor is not as critical as water quality although this species does look particularly effective in a well-planted tank with a dark substrate. To see it at its best a biotope-style set-up can also make an interesting project. A soft, sandy substrate is probably the best choice to which can be added a few driftwood roots and branches, placed in such a way that plenty of shady spots are formed. If you can't find driftwood of the desired shape common beech or oak is safe to use if thoroughly dried and stripped of bark.

The addition of dried leaf litter (beech, oak or Ketapang almond leaves are all suitable; we like to use a mixture of all three) would further emphasise the natural feel and as well as offering even more cover for the fish brings with it the growth of microbe colonies as decomposition occurs. These tiny creatures can provide a valuable secondary food source for fry whilst the tannins and other chemicals released by the decaying leaves are thought to be beneficial for blackwater fish species such as this. Certainly Brevibora dorsiocellata is known to display more intense colouration in tannin-stained water, and leaves can be left in the tank to break down fully or removed and replaced every few weeks.

Allow the wood and leaves to stain the water. A small net bag filled with aquarium-safe peat can also be added to the filter or hung over the edge of the tank to aid in the simulation of black water conditions. Alternatively obtain some genuine peat fibre and simply drop a few handfuls into the tank. This will become completely saturated with water after a few days and sink to the bottom where it can look really effective. Provided a good routine of water maintenance is practiced no adverse effects should occur using either peat or leaves in an aquarium.

This species will do best under fairly dim lighting. You could add some Asian plants that can survive under such conditions such as Microsorum pteropus, Taxiphyllum barbieri or perhaps some potted Cryptocorynes. A few patches of floating vegetation would be really useful to diffuse the light entering the tank too.

68 - 77°F/20 - 25°C

The widely available, captive-bred fish are quite adaptable and should be happy within the range 5.0 - 7.5. If you have the opportunity to purchase wild specimens they are likely to do best on the acidic side of neutral.

1 - 10°H

Stomach analyses of wild specimens have revealed it to be a micropredator feeding on small insects, worms, crustaceans and other zooplankton. In the aquarium it will accept dried foods of a suitable size but should not be fed these exclusively. Daily meals of small live and frozen fare such as Daphnia, Artemia and suchlike will result in the best colouration and encourage the fish to come into breeding condition.

This species is very peaceful indeed making it an ideal resident of the well-furnished community tank. As it places no special demands in terms of water chemistry it can be combined with many of the most popular fish in the hobby including other small cyprinids as well as tetras, livebearers, dwarf cichlids, catfish and loaches. As always when selecting a compatible community of fish thorough research is essential and its small adult size must be a consideration. In a biotope set-up you could try it alongside other Malaysian or Bornean blackwater species. There are many suitable choices but some of the more commonly exported examples include Puntius lineatus , P. pentazona , Trigonopoma pauciperforatum , Rasbora einthovenii  and Pangio species. It also makes an ideal companion for shy anabantoids such as Sphaerichthys or the more diminutive Betta species.

It's a schooling species by nature and really should be kept in a group of at least 8-10 specimens. Maintaining decent numbers will not only make the fish less nervous but will result in a more effective, natural-looking display. Males will also display their best colours as they compete with one other for female attention.

Mature females are noticeably rounder-bellied and often a little larger than males.

Like many small cyprinids this species is an egg-scattering, continuous spawner that exhibits no parental care. That is to say when the fish are in good condition they will spawn often and in a densely-planted, mature aquarium it is possible that small numbers of fry may start to appear without human intervention.

However if you want to increase the yield of fry a slightly more controlled approach is required. The adult group can still be conditioned together but one or more long, shallow, say 18" x 10" x 10"/45cm x 25cm x 25cm/29.5 litre containers should also be set up and half-filled with water. These should be very dimly lit and the base covered with some kind of mesh of a large enough grade so that the eggs can fall through it but small enough so that the adults cannot reach them. The widely available plastic 'grass'-type matting can also be used and works very well. The water itself should be of slightly acidic to neutral pH with a temperature towards the upper end of the range suggested above. A small power filter can be added initially and this should be positioned so that the flow is directed down the full length of the tank.

When the adult fish are well-conditioned and the females appear full of eggs one or two pairs should then be introduced to each container. Spawning can be initiated by adding small amounts of cool water every few hours in such a way that the tank is gradually topped up and feeding small amounts of live and frozen foods. Several spawning events will usually occur before a female is spent of eggs.

The adults will eat any eggs they find and are best removed after a couple of days at which point the power filter should be switched for a mature sponge-type unit in order to avoid fry being sucked into the mechanism. Incubation is temperature-dependant to an extent but usually takes between 18 and 48 hours with the young free-swimming 24 to 48 hours later. Initial food should be Paramecium or similar introducing Artemia nauplii and/or microworm once the fry are large enough to accept them.

Brevibora dorsiocellata is sometimes sold with the alternative trade names of 'green-eyed' or 'hi-spot' rasbora. There appear to exist several geographical forms of the species at least two of which have been seen in the trade. The most common is the rather plain-coloured fish that is produced commercially in large numbers and has gained popularity due to the bright green/blue reflective patch in the lower part of the eye. The other is only available from time-to-time and in all likelihood is exclusively wild caught. This one is particularly attractive because the caudal peduncle and base of the caudal fin are suffused with a russet red colouration, the extent and intensity of which can vary depending on the mood/condition and spawning behaviour of the fish.

None of these variants are likely to represent the subspecies known for many years as Rasbora d. macrophthalma; that fish is probably distinct with work by Grant (2002) revealing it to possess some notable morphological differences when compared with B. dorsiocellata. Most obviously an adult can measure 2.4"/6cm so it is a much larger fish, the eye is bigger, the origin of the dorsal fin is adjacent or just posterior to the insertion of the first ventral fin ray (versus noticeably anterior) and there is an area of yellow/green colouration in the dorsal fin anterior to the dark marking which blends into a white posterior blotch (vs. anterior area predominantly white and posterior blotch more clearly-defined from dark dorsal marking).

Rainboth's 'Fishes of the Cambodian Mekong' characterised members of Rasbora by possession of an unbranched, non-spiny first dorsal fin ray and seven soft dorsal rays, origin of the dorsal fin in the middle of the body, five branched anal fin rays, a small mouth not extending below the eye and a lack of barbels. It's long been recognised as a polyphyletic lineage as noted by Kottelat (1999) amongst others, and in 2009 the results of a phylogenetic analysis by T. Y. Liao et al. suggested a number of changes in order to improve the taxonomy. The authors found species of rasborin genera to actually represent a monophyletic grouping existing in six clades and erected four new genera (all containing former members of Rasbora) in order to preserve monophyly of the existing groups i.e. Boraras, Horadandia, Rasbora, Rasboroides and Trigonostigma.

According to the authors the first two clades are monotypic; R. brittani should now be referred to as Kottelatia brittani  and R. dorsiocellata as Brevibora dorsiocellata. The third clade comprises Boraras brigittae , Horadandia atukorali , Rasboroides vaterifloris , Trigonostigma heteromorpha  and three species previously included in Rasbora but also moved into new genera; Trigonopoma gracile , T. pauciperforatum  and Rasbosoma spilocerca . The results for B. brigittae  and T. heteromorpha  were found to be inconclusive in some respects and further work regarding their phylogenetic position was recommended.

The fourth clade includes Rasbora semilineata, R. borapetensis , R. rubrodorsalis  and an undescribed fish similar to R. beauforti. Clade five consists of R. daniconius, R. hubbsi, R. paucisqualis, R. wilpita , R. kobonensis, R. ornata and R. cf. daniconius. Clade six, meanwhile, is subdivided into two groupings. The first contains R. einthovenii , R. elegans  and R. cephalotaenia  and the second R. lateristriata, R. argyrotaenia , R. volzii, R. paviana , R. rasbora  (plus an undescribed, similar fish), R. caudimaculata  and R. trilineata . As this final clade contains the type species (see below) its members retain the generic name Rasbora as do clade five species because they don't differ sufficiently to warrant a the erection of a new genus/genera.

Unfortunately many species weren't included in the analysis, meaning inevitable questions are raised regarding the correct placement of the 40 or so other Rasboras, in particular. As the genus had previously been split into various 'species groups' (groups of closely-related species) dating back to Brittan (1972, who referred to them as 'species complexes') Liao et al. proposed the following arrangement whilst noting it may be subject to change with further phylogenetic studies:

R. semilineata species group: R. semilineata, R. borapetensis , R. rubrodorsalis .
R. trifasciata species group: R. trifasciata, R. amplistriga, R. bankanensis, R. dies, R. ennealepis, R. hubbsi, R. johannae, R. meinkeni, R. paucisqualis, R. rutteni, R. sarawakensis , R. taytayensis, R. tobana, R. tuberculata.
R. daniconius species group: R. daniconius, R. caverii, R. kobonensis, R. labiosa, R. ornata, R. wilpita .
R. einthovenii  species group: R. einthovenii , R. cephalotaenia , R. elegans , R. jacobsoni, R. kalochroma , R. kottelati , R. nematotaenia, R. tubbi.
R. argyrotaenia  species group: R. argyrotaenia , R. aprotaenia, R. aurotaenia, R. baliensis, R. borneensis, R. bunguranensis, R. dusonensis , R. evereti, R. hobelmani, R. hossi, R. lateristriata, R. laticlavia, R. leptosoma, R. philippina, R. septentrionalis, R. spilotaenia, R. steineri, R. tawarensis, R. tornieri, R. volzii.
R. sumatrana species group: R. sumatrana, R. atridorsalis, R. calliura, R. caudimaculata , R. dorsinotata , R. notura, R. paviana , R. rasbora , R. subtilis, R. trilineata , R. vulgaris.

Not classified: R. beauforti, R. chrysotaenia, R. gerlachi (validity in question), R. kalbarensis, R. reticulata, R. vulcanus  (possibly not Rasboras) and R. zanzibarensis (identity in question).

The identity of the type species, often given as R. rasbora  in the past, is no longer in question; when Bleeker first referred to the name Rasbora in 1859 only four nominal members were included of which R. cephalotaenia  (known as Leuciscus cephalotaenia at the time) should be considered the type. Howes (1980) suggested the separation of a number of species into the new genus Parluciosoma with type species P. (Rasbora) argyrotaenia but the monophyly of that grouping was not recovered by Liao et al.

Literature cited

1. Mayden, Richard L.; Tang, Kevin L.; Conway, Kevin W.; Freyhof, Jörg; Chamberlain, Sarah; Haskins, Miranda; Schneider, Leah; Sudkamp, Mitchell; Wood Robert M.; Agnew, Mary; Bufalino, Angelo; Sulaiman, Zohrah; Miya, Masaki; Saitoh, Kenji; He, Shunping. 2007 - J. Exp. Zool. (Mol. Dev. Evol.) 308B: 1–13.
   Phylogenetic relationships of Danio within the order Cypriniformes: a framework for comparative and evolutionary studies of a model species.
2. KOTTELAT, M. 1999 - Raffles Bull. Zool. 47(2): 591-600.
   Nomenclature of the genera Barbodes, Cyclocheilichthys, Rasbora and Chonerhinos (Teleostei: Cyprinidae and Tetraodontidae), with comments on the definition of the first reviser.
3. www.fishbase.org
4. Grant, S. 2002 - BSSW Report Heft 4/2002 Seite 13.
   Zur Identität und Gültigkeit von Rasbora macrophthalma MEINKEN, 1951 (Cyprinidae, Rasborinae).