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Barilius bakeri (DAY, 1865)

Etymology

bakeri: named for Rev. H. Baker, who collected specimens of this species from Mundikyum (see ‘Distribution’).

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

Endemic to the Western Ghats range of mountains, southwestern India.

Type locality is given by Day as ‘the hills at Mundikyum is given by Day as ‘Mundikyum, Cochin, India’ which appears to correspond to the small town now known as Mundakayam, in Kottayam District of Kerala state, South India.

The Manimala river flows through the town and eventually empties into Vembanad lake.

Additional records exist from most rivers draining the western side of the Western Ghats in both Kerala and southern Karnataka states and B. bakeri is the commonest member of the genus to be found in these systems.

In Kerala records exist from the Periyar, Kabini, Chalakudy, Valapatanam, Chaliyar, Neyyar, Pampa, Vamanapuram, Kallada, Ithikkara, Karamana, Bharatapuzha, Muvattupuzha, Meenachil, Manimala, Achankovil, Pambar, Chandragiri, Karyangode, Kuppam, and Bahavani river systems.

In Karnataka it’s known only from the Sharavathi River basin, and it also occurs the Indira Gandhi Wildlife Sanctuary plus the Chittar, Periyar, and Pampa river basins in Tamil Nadu state.

Habitat

Inhabits well-oxygenated, low-to-medium gradient, moderate to fast-flowing rivers and streams with substrates of gravel, cobbles, larger boulders and exposed bedrock.

Many such habitats are being polluted by domestic and industrial waste or degraded by introduction of exotic species and large-scale sand mining operations.

In the Tunga river sympatric species include Devario malabaricusDanio  rerioRasbora daniconiusDawkinsia aruliusD. assimilisHaludaria fasciataPethia tictoPuntius sahyadriensis, ‘Puntius  narayaniSystomus saranaTor kudreeGarra  mullyaPsilorhynchus tenuraSchistura  nilgiriensisS.  semiarmatusS.  denisonii, Nemacheilus anguillaAplocheilus blockiiA.  lineatusPristolepis marginata, and Channa gachua.

Maximum Standard Length

110 – 130 mm.

Aquarium SizeTop ↑

Requires a large aquarium with minimum surface area of 150 ∗ 60 cm or equivalent.

Maintenance

The aquarium should ideally be designed to resemble a flowing stream or river with a substrate of variably-sized rocks, sand, fine gravel, and some larger water-worn boulders.

This can be further furnished with driftwood roots and branches if you wish but be sure to leave plenty of open swimming space.

While the majority of aquatic plants will fail to thrive in such surroundings hardy genera such as Microsorum, Bolbitis, or Anubias spp. can be grown attached to the décor.

Like many fishes that naturally inhabit running waters it’s intolerant to the accumulation of organic wastes and requires spotless water at all times in order to thrive.

It also does best if there is a high proportion of dissolved oxygen and moderate degree of water movement so external filters, powerheads, airstones, etc., should be employed as necessary.

As stable water conditions are obligatory for its well-being this fish should never be added to biologically-immature aquaria and weekly water changes of 30-50% aquarium volume should be considered mandatory.

A tightly-fitting cover is also essential as Barilius spp. are prodigious jumpers.

Water Conditions

Temperature18 – 26 °C

pH6.0 – 7.5

Hardness18 – 179 ppm

Diet

Barilius spp. are near-exclusive surface-feeders preying mostly on flying insects in nature with some small fishes and benthic invertebrates probably taken as well but in the aquarium they’re largely unfussy and will accept most foods.

Good quality dried products can be offered but should be supplemented with regular meals of live and frozen fare such as bloodwormArtemia, chopped earthworms, etc., for the best colouration and conditioning.

Drosophila fruit flies and small crickets are also suitable provided they’re gut-loaded prior to use.

Behaviour and CompatibilityTop ↑

Unsuitable for the general community due to its environmental requirements and likely to outcompete or intimidate slow-moving and less bold species at meal times since it’s an extremely fast swimmer and vigorous feeder.

Much smaller fishes should also be omitted as they may be predated upon.

The best tankmates are similarly-sized, robust, open-water dwelling cyprinids such as Dawkinsia, other Barilius or larger Devario and Rasbora spp. while bottom-dwellers could consist of Garra, Crossocheilus, Botia and Schistura spp., for example.

We suspect many characids and loricariid catfishes would also work well but be sure to perform thorough research before purchase.

Although gregarious by nature this is a shoaling rather than schooling species which develops a distinct pecking order and therefore should always be maintained in a group of five or more.

If only two or three are purchased the subdominant fish may be bullied incessantly whereas solitary specimens can become aggressive towards similar-looking species.

Sexual Dimorphism

Adult females are less-brightly-coloured, tend to grow a little larger and are thicker-bodied than males, especially when gravid.

Nuptial males develop breeding tubercules on the head and orange pigmentation in the lower portion of the body.

Reproduction

Spawning can apparently be stimulated by performing large, cool water changes but as far as we know there exist no reports of fry being raised.

NotesTop ↑

This species is traded under several names including ‘royal danio’, ‘blue-spotted hill trout’, and ‘blue-dotted mirror fish’.

It’s often confused with the congener B. canarensis but can be told apart by possession of a silvery-blue (vs. bluish-green) base body colour, a variable number of small, blue spots running in one or more rows along the flanks (vs. usually two or more, rarely one, rows of large, vertically-elongate spots on the flanks), and white marginal bands in the dorsal and anal fins (vs. orange to red marginal bands in the dorsal and anal fins).

Additional diagnostic characters as given by Collins et al. (2012) include: possession of one minute pair of barbels; lateral line complete; 10½-11½ branched dorsal-fin rays; 13½ branched anal-fin rays; upper caudal-fin lobe with submarginal dark blotch anteriorly.

It’s also worth noting that the blue spots on the flanks get progressively smaller as the fish age and can appear much larger in young specimens.

There also exist intermediate populations which match most diagnostics for B. bakeri but possess orange dorsal and anal fin margins, or have white fin margins with vertically-elongate flank markings as in B. canarensis.

Some of these have been described in the past by Day and Jerdon but are not currently considered valid and require additional study (R. Kumar, pers. comm.).

The generic placement of Barilius spp. has been open to question since Howes (1980) concluded that the grouping was not monophyletic and identified two separate lineages.

The first group contained B. barila, the type species, plus B. bendelisisB. radiolatus, B. vagra, and B. shacra, while the second included all other species, and initially these were referred to the subdivisions ‘group i’ and ‘group ii’ within Barilius itself.

The composition of these groups is confusing since in a later work Howes (1983) included B. evezardi and B. modestus in ‘group i’ whilst omitting B. bendelisis, B. radiolatus, and B. shacra, apparently without explicitly stating why.

Rainboth (1991) assigned the members of Howe’s ‘group ii’ to the revalidated generic name ‘Opsarius‘ based on the fact it was the oldest available with ‘group i’ species retaining the name Barilius due to the presence of the type species.

This system has been followed by some subsequent authors, e.g., Tang et al. (2010), Collins et al. (2012) though does not appear to have found wider usage since most species are still referred to Barilius in both scientific and aquarium literature.

These issues were discussed by Tang et al. (2010) relative to the results obtained in their phylogenetic analysis of the putative subfamily Danioninae in which that assemblage was found to comprise three main lineages or ‘tribes’ of which Barilius and Opsarius were included in the tribe Chedrini.

However, since no specimens of the type species of either Barilius or Opsarius (B. barila and O. tileo, respectively) were included in the study the taxonomic status and composition of both groupings remains undetermined.

The authors did conclude that Opsarius sensu Rainboth represents a polyphyletic assemblage in that putative members of the genus appeared in three different places in their phylogenetic tree, although all were recovered within Chedrini.

Specifically Rainboth’s O. koratensis was recovered as sister group to all other members of the tribe Chedrini except Malayochela and Nematobramis spp.

A second group was formed by his O. bakeri, O. canarensis, and an undescribed species listed as O. cf. bakeri with all other species, including O. bendelisis, forming a third cluster.

Depending on the results of additional taxon sampling and the phylogenetic position of O. tileo new names may be required for two of these lineages, therefore all of them are referred to Barilius here on SF pending confirmation of their correct placement.

References

  1. Day, F., 1865 - Proceedings of the Zoological Society of London 1865 (part 1): 286-318
    On the fishes of Cochin, on the Malabar Coast of India. Part II. Anacanthini.
  2. Collins R. A., K. F. Armstrong, R. Meier, Y. Yi, S. D. J. Brown, R. H. Cruickshank, S. Keeling, and C. Johnston, 2012 - PLoS ONE 7(1): e28381
    Barcoding and border biosecurity: identifying cyprinid fishes in the aquarium trade.
  3. Howes, G. J., 1980 - Bulletin of the British Museum (Natural History) : Zoology series 37(3): 129-198
    The anatomy, phylogeny and classification of bariliine cyprinid fishes.
  4. Liao, T-Y, S. O. Kullander, and F. Fang, 2011 - Journal of Zoological Systematics and Evolutionary Research 49(3): 224-232
    Phylogenetic position of rasborin cyprinids and monophyly of major lineages among the Danioninae, based on morphological characters (Cypriniformes: Cyprinidae).
  5. Nath, P., D. Dam, and A. Kumar, 2010 - Records of the Zoological Survey of India 110(3): 19-33
    A New Fish Species of the Genus Barilius (Cyprinidae: Rasborinae) from River Siang, D'Ering Memorial Wildlife Sanctuary, Arunachal Pradesh, India.
  6. Raju Thomas, K., M. J. George, and C. R. Biju, 2002 - Journal of the Bombay Natural History Society 99(1): 47-53
    Freshwater fishes of southern Kerala with notes on the distribution of endemic and endangered species.
  7. Tang, K. L., M. K. Agnew, W. J. Chen., M. V. Hirt, T. Sado, L. M. Schneider, J. Freyhof, Z. Sulaiman, E. Swartz, C. Vidthayanon, M. Miya, K. Saitoh, A. M. Simons, R. M. Wood, and R. L. Mayden, 2010 - Molecular Phylogenetics and Evolution 57(1): 189-214
    Systematics of the subfamily Danioninae (Teleostei: Cypriniformes: Cyprinidae).

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