Dawkinsia exclamatio (PETHIYAGODA & KOTTELAT, 2005)

SynonymsTop ↑

Puntius exclamatio Pethiyagoda & Kottelat, 2005

Etymology

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

exclamatio: in reference to this species’ colour pattern of this fish, which resembles an exclamation mark when viewed ‘snout-down’.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

Type locality is ‘3 kilometers downstream of Thenmalai Dam, on Thenmalai-Trivandrum Road, Kallada River, Kerala, India’, and it may be endemic to the Kallada system which flows through southern Kerala state before emptying into the coastal Ashtamudi Lake.

Habitat

Inhabits various riverine habitat types, and conditions likely to vary depending on time of year with significant increases in water volume, chemistry, and turbidity likely during the annual monsoons.

In March 1996 the type locality contained clear, shallow slowly-flowing (depth < 50 cm) water and D. exclamatio was collected among granite boulders alongside the congener D. assimilis (Pethiyagoda and Kottelat, 2005a).

Maximum Standard Length

80 – 100 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

Not difficult to keep in a well-maintained set-up, though we recommend aquascaping the tank to resemble a flowing stream or river with a substrate of variably-sized, water-worn rocks, sand, fine gravel and perhaps some small boulders.

This can be further furnished with driftwood roots or branches, and while the majority of aquatic plants will fail to thrive in such surroundings hardy types such as Microsorum, Bolbitis or Anubias spp. can be grown attached to the décor.

Since it naturally occurs in relatively pristine habitats it’s intolerant to accumulation of organic pollutants and requires more-or-less spotless water in order to thrive.

Though torrent-like conditions are unnecessary it also does best if there is a high proportion of dissolved oxygen and moderate water movement, while weekly water changes of 30-50% tank volume should be considered routine.

Water Conditions

Temperature: 19 – 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 always, thorough research is the best way to avoid problems when selecting a compatible fish community.

It’s a schooling species by nature so ideally 8-10 specimens should be purchased, though it will also group together with related species.

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 males concentrate on maintaining their hierarchical position within the group.

Sexual Dimorphism

Adult males develop a more intense colour pattern than females, exhibit noticeable tubercules on the head when in spawning condition, and some individuals develop filamentous rays in the dorsal-fin.

Adult females tend to grow a little larger, are heavier-bodied, and less colourful.

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 ↑

D. exclamatio is rare in the aquarium hobby but occasionally shipped as bycatch among shipments of similar-looking species such as D. assimilis.

It was formerly included in the genus Puntius and 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. exclamatio is told apart from all other Dawkinsia spp. by the following suite of characters: presence of two black blotches on each flank, one 2-3 scales wide commencing on and above lateral line scales 6 and 7, the other about 1½ scales high commencing on lateral line slightly anterior to or above anal-fin origin, on about lateral line scale 13 and extending along the caudal peduncle to the caudal-fin base; caudal peduncle blotch horizontally-elongate and tear-drop shaped.

It’s the only member of the group to possess two such blotches, all others having one or three.

There is a case, however, to suggest that D. exclamatio is not actually a distinct taxon but rather a natural hybrid between D. assimilis and a D. arulius-like fish (possibly D. rubrotinctus)  which occur together at its type locality in the Kallada River at Thenmalai.

The potential of hybridisation is evidenced by the somewhat intermediate colour pattern in that it possesses a (roughly) W-shaped mid-lateral blotch, a feature shared with D. rubrotinctus, but  also a laterally-elongated blotch on the caudal peduncle as in some other congeners, a unique combination within the assemblage.

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 at the moment.

References

1. Pethiyagoda, R. and M. Kottelat, 2005a - 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.
2. 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).
3. Marcus Knight, J. D., 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.
4. Pethiyagoda, R., 2013 - Zootaxa 3646(2): 199
   Haludaria, a replacement generic name for Dravidia (Teleostei: Cyprinidae).
5. Pethiyagoda, R. and M. Kottelat, 2005b - Raffles Bulletin of Zoology Supplement 12: 145-152
   The identity of the south Indian barb Puntius mahecola (Teleostei: Cyprinidae).
6. 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).
7. Rema Devi, K., T. J. Indra, and J. D. Marcus 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.