Kottelatia brittani

Cyprinidae

This species has a puzzling distribution if the occurence records are studied. It's normally said to be native to Peninsular Malaysia plus the Greater Sunda Islands of Sumatra and Borneo but collection details are scarce. Whilst records from the Kapuas drainage in West Kalimantan (Kalimantan Barat) province, Borneo seem to be legitimate those from the type locality at the town of Selamat, Johor river, Johor state, Peninsular Malaysia are probably wrong because the Johor river actually runs nowhere close to Selamat. The type specimens themselves were obtained via a Singapore wholesaler so it is possible that a mistake was made as we can find no other record of the species in Peninsular Malaysia. Its existence in Sumatra is now confirmed however (Tan and Kottelat, 2009), specimens having been collected from the Batang Hari river, Jambi province, and it may well turn out to be endemic to the island.

Presumably inhabits quiet forested streams and tributaries containing relatively clear water although we have been unable to obtain any definitive information to date.

2.4"/6cm.

A tank measuring 24" x 15" x 12"/60cm x 37.5cm x 30cm/70.8 litres is just about big enough to house a small group.

Choice of decor is not as critical as water quality although small rasboras tend to show better colouration when maintained in a well-planted set-up with a dark substrate. The addition of some floating plants and driftwood roots or branches to diffuse the light entering the tank also seems to be appreciated and adds a more natural feel. Do not add this fish to a biologically immature tank as it can be susceptible to swings in water chemistry and be sure to add a tightly-fitting cover as like most rasboras it's an accomplished jumper.

73 - 79°F/23 – 26°C

Generally said to do best under acidic conditions but SF members who have kept the species say that it does best at around neutral pH. A value within the range 6.5 - 7.5 should be ok.

1 - 5°H

Likely to be a micropredator feeding on small insects, worms, crustaceans and other zooplankton in nature. 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 along with good quality flakes and granules will result in the best colouration and encourage the fish to come into breeding condition.

This species makes an ideal addition to a peaceful community of Southeast Asian/Indian fish such as similarly-sized Rasbora, Puntius, botiid/cobitid loaches and gouramis of the genus Trichogaster but will not compete well with much larger or more boisterous species. In a biotope set-up you could try it alongside other inhabitants of Bornean blackwaters. 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 it in 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.

We're not sure if it has been bred in the hobby although it should certainly be possible. Like most 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 and we suggest beginning with an approach that has proven successful for other small members of the genus. The adult group can still be conditioned together but one or more long, shallow, say 18" x 10" x 10"/45cm x 20cm x 20cm/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 for other species. The water itself should be of slightly acidic to neutral pH with a temperature towards the upper end of the range suggested above. An internal 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 probably occur before a female is spent of eggs.

The adults will likely 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 in related Rasbora eggs 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.

This species is a rare find but may be seen on sale with the trade name 'head and tail light rasbora' when it is available. It has been confused with the similar-looking Rasbora kalbarensis on occasion but can be identified by its larger adult size, more pointed head profile and intense orange/red blotches at the caudal peduncle. The body of R. kalbarensis is also suffused with a distinguishing pinkish hue. Furthermore Tan and Kottelat (2009) note that K. brittani lacks the symphyseal knob on the lower jaw, a small growth present in all Rasbora species.

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. www.petfrd.com
5. Tan, H. H. and M. Kottelat. 2009 - Ichthyol. Explor. Freshwat. 20(1): 13-69.
   The fishes of the Batang Hari drainage, Sumatra, with description of six new species.
6. Liao, T. Y., Kullander, S. O. and F. Fang. 2009 - Zoologica Scripta Early View (Articles online in advance of print).
   Phylogenetic analysis of the genus Rasbora (Teleostei: Cyprinidae).