Dawkinsia rubrotinctus (JERDON, 1849)

SynonymsTop ↑

Systomus rubrotinctusJerdon, 1849; Puntius rubrotinctus (Jerdon, 1849)

Etymology

Dawkinsia: named for Richard Dawkins, for ‘his contribution to the public understanding of science and, in particular, of evolutionary science’.

rubrotinctus: from the Latin ruber, meaning ‘red’, and tinctus, meaning ‘coloured, tinged’.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

Type locality is the Mananthavadi River, a tributary of the Kabini river system within the larger Cauvery watershed in Wayanad District of Kerala state, southern India, but it’s now considered widespread throughout the Cauvery drainage in the states of Karnataka, Kerala and Tamil Nadu.

The full extent of its range remains unconfirmed since similar-looking fishes have been recorded from the Kallada River in southern Kerala, in particular, where they may form natural hybrids with the congener D. assimilis (see ‘Notes’).

Habitat

No precise data is available but it’s certainly a pelagic, riverine species with habitats likely to vary depending on locality and time of year with two annual monsoons causing increases in water depth, flow and turbidity in many rivers draining the Western Ghats.

Other species found in the same general area include Pethia conchonius, Puntius denisonii, Haludaria fasciata, Dawkinsia arulius, D. assimilis, D. filamentosa, Barilius bakeri, B. bendelisis, B. canarensis, Devario malabaricus, Esomus danricus, Garra mcclellandi, G. hughi, Bhavania australis, Travancoria jonesi, Mesonoemacheilus guentheri, M. triangularis, Schistura denisonii, Lepidocephalichthys thermalis, Batasio travancoria, Mystus armatus, M. canarensis, Glyptothorax annandalei, Aplocheilus lineatus, Parambassis thomassi, Etroplus canarensis, E. maculatus, Sicyopterus griseus, Pseudosphromenus dayi, Channa striata, and Carinotetraodon travancoricus.

Maximum Standard Length

80 – 90 mm.

Aquarium SizeTop ↑

An aquarium with base measurements of at least 120 ∗ 45 cm or equivalent should be the smallest considered for long-term care.

Maintenance

Fairly easy to maintain provided a dedicated maintenance routine is adhered to, with choice of décor is more-or-less down to personal taste.

A natural-style arrangement could include a substrate of sand or gravel with plenty of larger, water-worn rocks and pebbles plus some driftwood roots or branches.

Lighting can be relatively subdued and plants able to grow in such conditions such as Microsorum, Taxiphyllum or Anubias spp. may be added if you wish. These have an added benefit as they can be attached to pieces of décor.

Although turbulent conditions aren’t required this species fares best when the water is well-oxygenated with a degree of flow meaning use of an over-sized external filter or two is recommended.

In terms of maintenance weekly water changes of 30-50% tank volume should be considered routine.

Water Conditions

Temperature: 18 – 25 °C

pH: 6.0 – 7.5

Hardness: 36 – 179 ppm

Diet

Probably a foraging omnivore feeding on a variety of worms, insects, crustaceans, plant material, and other organic debris in nature.

In the aquarium it’s easily-fed but a balanced diet comprising regular meals of small live and frozen foods such as bloodworm, Daphnia, and Artemia alongside good quality dried flakes and granules will being about optimal condition and colours .

Behaviour and CompatibilityTop ↑

An ideal addition to a peaceful community of riverine species alongside other schooling or shoaling cyprinids plus botiid, cobitid, nemacheilid, and balitorid loaches.

If geography isn’t an issue it can actually be combined with most peaceful fish of a size too large to be considered food and that have a bold enough disposition to not be intimidated by its size and active nature.

As usual, thorough research is the best way to avoid problems when selecting compatible fish communities.

It’s a schooling species by nature so ideally 8-10 specimens should be purchased. Maintaining it in decent numbers will not only make the fish less skittish but will result in a more effective, natural looking display.

In addition, any aggressive behaviour will normally be contained as the fish concentrate on maintaining their hierarchical position within the group.

Sexual Dimorphism

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

Reproduction

Possibly unrecorded, but recommendations for closely-related species are as follows:

Like most small cyprinids Dawkinsia spp. are egg-scattering free spawners exhibiting no parental care.

When in good condition they will spawn often and in a mature aquarium it’s possible that small numbers of fry may start to appear without intervention, although if you want to maximise yield a more controlled approach is required.

The adult group can still be conditioned together but a separate aquarium should be set up and filled with mature water.

This should be dimly-lit and the base covered with some kind of mesh of a large enough grade so that the eggs can fall through but small enough so that the adults cannot reach them. The widely available plastic ‘grass’-type matting can also be used and works well, as does a layer of glass marbles.

Alternatively filling much of the tank with a fine-leaved plant such as Taxiphyllum spp. or spawning mops can also return decent results.

The water itself should be of slightly acidic to neutral pH with a temperature towards the upper end of the range suggested above, and an air-powered sponge filter or air stone(s) should also be included to provide oxygenation and water movement.

When the adults are well-conditioned and the females appear gravid one or two pairs should then be introduced, and spawning should take place the following morning.

An alternative is to spawn the fish in a group with half a dozen specimens of each sex being a good number, although a larger aquarium may be necessary.

In either situation the adults will probably eat the eggs given the chance and should be removed as soon as any are noticed.

These should hatch in 24 – 48 hours with the fry free swimming around 24 hours later.

They require microscopic food for the first few days until large enough to accept microworm, Artemia nauplii or suchlike.

NotesTop ↑

This species may have appeared in the aquarium trade under the misapplied names Puntius arulius and P. tambraparniei in the past, both of which are also now classified within Dawkinsia.

See the relevant profiles for D. arulius and D. tambraparniei for additional information regarding that confusion, since here we concentrate on D. rubrotinctus.

It was initially described by Jerdon in 1849 but placed in synonymy with P. arulius by Day (1878), where it remained for over 100 years before being revalidated by Knight et al. (2011) and placed within the Puntius filamentosus ‘group’ of related species which also contained P. arulius, P. assimilis, P. exclamatio, P. filamentosus, P. rohani, P. rubrotinctus, P. singhala, P. srilankensis, and P. tambraparniei, but all of these were moved to the new genus Dawksinia by Pethiyagoda et al. (2012).

Dawksinia species are defined by the following combination of characters: adult size normally  80-120 mm SL; rostral barbels absent; maxillary barbels present or absent; last unbranched dorsal-fin ray smooth; 4 unbranched and 8 branched dorsal-fin rays; 3 unbranched and 5 branched anal-fin rays; lateral line complete, with 18-22 scales on body; gill rakers simple, acuminate (not branched or laminate); no antrorse predorsal spinous ray; free uroneural present; 4-5 supraneurals; 15 precaudal and 14-17 caudal vertebrae; post-epiphysial fontanelle absent; infraorbital 3 slender, not overlapping preoperculum; juvenile (< 50 mm SL) colour pattern consisting of three black bars on body, retained in adults of some species; a black, horizontally elongate blotch on the caudal peduncle in adults.

D. rubrotinctus is easily told apart from most congeners since it possesses three, vs. 2, dark markings on the body, a character shared only with D. arulius, D. srilankensis, and D. tambraparniei.

However in P. rubrotinctus the three markings are relatively small and well-defined, measuring just two scales high and three wide, whereas in the other three species they are much larger and more diffuse.

It further differs from D. arulius in the following characters: dorsal to hypural distance 49.8 – 54.6 % SL vs. 57.3 – 57.6 % SL; interorbital width 28.4 – 35.6 % HL vs. 39.1 – 39.7 % HL; 10(8) – 11(4) gill rakers in the first gill arch vs. 8(3).

It differs from D. tambraparniei and D. srilankensis by possession of a more terminal mouth vs. sub-terminal (D. tambraparniei) or inferior (D. srilankensis) and lacking filamentous extensions to the dorsal-fin in males (vs. presence in D. tambraparniei and D. srilankensis).

It also has a longer maxilla than D. tambraparniei (26.5 – 32.3 % HL vs. 19.0 – 21.6 % HL) and is further separated from D. srilankensis by the following characters: head length 28.3 – 32.8 % SL vs. 24.8 – 26.7 % SL; body depth 34.9 – 41.8 % SL vs. 28.0 – 31.9 % SL; interorbital width 28.4 – 35.6 % HL vs. 37.8 – 42.5 % HL; barbels 7.3 – 13.4 % HL vs. 0.0 – 1.8 % HL.

The precise relationships within the genus are still open to question in some respects with Knight et al. (2011) suggesting that members may hybridise naturally at some localities.

For example, a D. arulius-like fish (possibly D. rubrotinctus) co-occurs with D. assimilis in the Kallada River at Thenmalai, which also happens to be the type locality of D. exclamatio.

The latter is somewhat anomalous since it’s the only Dawksinia species other than D. rubrotinctus to feature a (roughly) W-shaped mid-lateral blotch, but also has a laterally-elongated blotch on the caudal peduncle as in other genus members.

D. exclamatio should also have a sub-terminal mouth and lack dorsal-fin filaments but some specimens possess a terminal mouth and/or possess dorsal filaments, and one specimen also had black caudal-fin tips as typically seen in D. filamentosa, whereas the description states that the fin tips are only dusky and lack distinctive markings.

Forms apparently intermediate between D. filamentosa and D. tambraparniei have also been collected where the two occur together in the Thamirabarani River, Tamil Nadu.

While no conclusions were reached because DNA testing was not performed, hybridisation between D. filamentosa and D. arulius in that river had previously been speculated and is a phenomenon known to be more common in the family Cyprinidae than in any other group of fishes, meaning future research may yield interesting results.

The genus Puntius was for a number of years viewed as a polyphyletic catch-all containing over 100 species of small to mid-sized cyprinid until Pethiyagoda et al. (2012) published a partial review covering South Asian members.

The majority of sub-Himalayan Puntius species were reclassified and new genera Dawkinsia, Dravidia, and Pethia erected to accomodate some of them, with the remainder either retained in Puntius or moved to the existing Systomus assemblage, though the definition of the latter was altered meaning some Southeast Asian species formerly placed there are no longer members.

It subsequently became clear that the name Dravidia was preoccupied by a genus of flesh fly, therefore the replacement name Haludaria was made available by Pethiyagoda (2013).

No species from Indochina, China, or Indonesia were included in the study meaning a significant number of former Puntius are currently classed as incertae sedis, i.e., of uncertain taxonomic placement, and this also applies to a number of South Asian species of unresolved status.

They’re perhaps best referred to as ‘Puntius‘ for the time being whereby the genus name is surrounded by quotation marks to denote its questionable usage, and that is the convention used here on SF.

References

1. Arunachalam, M. and J. A. Johnson, 2003 - Journal of the Bombay Natural History Society 99(3): 474-480
   A new species of Puntius Hamilton (Pisces: Cyprinidae) from Kalakad Mundanthurai Tiger Reserve, Tamil Nadu, India.
2. Knight, J. D. M., K. Rema Devi and V. Atkore, 2011 - Journal of Threatened Taxa 3(4): 1686-1693
   Systematic status of Systomus rubrotinctus Jerdon (Teleostei: Cyprinidae) with notes on the Puntius arulius group of fishes.
3. Kottelat, M. and H-H Tan, 2011 - Ichthyological Exploration of Freshwaters 22(3): 209-214
   Systomus xouthos, a new cyprinid fish from Borneo, and revalidation of Puntius pulcher (Teleostei: Cyprinidae).
4. Kurian Abraham, R., N. Kelkar and A. Biju Kumar, 2011 - Journal of Threatened Taxa 3(3): 1585-1593
   Freshwater fish fauna of the Ashambu Hills landscape, southern Western Ghats, India, with notes on some range extensions.
5. Pethiyagoda, R., 2013 - Zootaxa 3646(2): 199
   Haludaria, a replacement generic name for Dravidia (Teleostei: Cyprinidae).
6. Pethiyagoda, R. and M. Kottelat, 2005 - The Raffles Bulletin of Zoology Supplement 12: 127-144
   A review of the barbs of the Puntius filamentosus group (Teleostei: Cyprinidae) of southern India and Sri Lanka.
7. Pethiyagoda, R., M. Meegaskumbura, and K. Maduwage, 2012 - Ichthyological Exploration of Freshwaters 23(1): 69-95
   A synopsis of the South Asian fishes referred to Puntius (Pisces: Cyprinidae).
8. Raju Thomas, K., C. R. Biju, C. R. Ajithkumar and M. J. George, 2000 - Journal of the Bombay Natural History Society 97(3): 443-446
   Fish fauna of Idukki and Neyyar wildlife sanctuaries southern Kerala, India.
9. 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.
10. Rema Devi, K., T. J. Indra, and J. D. M. Knight, 2010 - Journal of Threatened Taxa 2(9): 1121-1129
    Puntius rohani (Teleostei: Cyprinidae), a new species of barb in the Puntius filamentosus group from the southern Western Ghats of India