Devario acuticephalus (HORA, 1921)

SynonymsTop ↑

Danio acuticephala Hora, 1921; Brachydanio acuticephala (Hora, 1921); Devario acuticephala (Hora, 1921)

Etymology

Devario: appears to be derived from a local vernacular name for the type species of the genus Cyprinus (now Devario) devario Hamilton, 1822.

acuticephala: from the Latin acutus, meaning ‘sharpened, sharp’, and cephalus, meaning ‘head’.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

Described from Manipur state, northeastern India and also known from neighbouring Nagaland state with type locality ‘On Ukjhang sang Road, 1 mile from Yaribuk, Manipur, Assam, India’.

In the original description Hora refers to it as ‘widely-distributed’ in the region but during an assessment conducted by the IUCN in 2010 it was recorded only from a handful of localities and restricted to an area of less than 15,000 square kilometres.

Most habitats lie within the Manipur river basin, including the tributary Iril and Khuga drainages, and the Dikhu watershed in Nagaland.

Habitat

Manipur is situated around 800 m AMSL and receives a great deal of rainfall between the months of May and October.

This species is likely to be restricted to small hill streams with substrates of gravel and variably-sized rocks and some marginal or over-hanging vegetation, while water flow is probably variable depending on time of year.

Maximum Standard Length

35 – 40 mm.

Aquarium SizeTop ↑

A tank with a base measuring 80 ∗ 30 cm or equivalent should be the minimum considered for this active species.

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

Though very fast flow is unnecessary it also prefers a relatively high proportion of dissolved oxygen and moderate water movement.

Weekly water changes of 30-50% volume should be considered routine, and the tank must have a very tightly-fitting cover as all Devario spp. are accomplished jumpers.

Water Conditions

Temperature: Air temperatures in Manipur vary from sub-zero in winter to around 89.6°F/32°C in summer so this species can be kept in an unheated tank in many countries, with a general range of 16 – 22 °C suggested. Both aeration and feeding should be increased during warmer months.

pH: 6.0 – 7.0

Hardness: 18 – 143 ppm

Diet

Almost certain to prey chiefly on insects and their larvae in nature although in the aquarium it’s a largely unfussy feeder and will accept most foods.

A good quality dried product can be used as the staple diet but this should be supplemented with regular meals of small live and frozen fare such as bloodworm, Daphnia, Artemia, etc., for the best colouration and conditioning.

Behaviour and CompatibilityTop ↑

This species is peaceful and can be maintained alongside other small,peaceful cyprinids.

Bottom-dwellers could include loaches from genera such as Lepidocephalichthys or Nemacheilus plus catfishes such as Akysis, Hara or Erethistes spp.

Freshwater gobies like Rhinogobius or Stiphodon spp. and many freshwater shrimp should also work.

Suitable options from Manipur, though not necessarily occurring sympatrically, include Devario aequipinnatus, Pethia conchonius, P. ticto, Barilius barila, Psilorhynchus balitora, Acanthocobitis botia, Lepidocephalichthys berdmorei, L. guntea, Erethistes pusillus and Trichogaster fasciata.

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

Sexual Dimorphism

Sexually mature females should be rounder-bellied, less colourful and a little larger than males.

Reproduction

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

When in good condition they will spawn often and in a well-planted, mature aquarium it’s possible that small numbers of fry may start to appear without intervention.

However if you want to maximise yield a more controlled approach is required.

The adult group can still be conditioned together but a smaller tank with a base measuring around 45cm x 30cm should also be set up and filled with mature water.

This 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 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 wool 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.

If ready spawning usually taking place within 24 hours, with the female tending to appear noticeably slimmer after the event, and after 48 hours the adults should be removed whether this is observed or not.

Incubation is temperature-dependant to an extent but typically lasts 24-36 hours with the young free-swimming a few days later.

Initial food should be Paramecium or similar, introducing Artemia nauplii, microworm, powdered dry foods, etc., once the fry are large enough to accept them.

NotesTop ↑

This species is rare in the aquarium hobby but traded on occasion.

D. apogon from Yunnan province, China is very similar in appearance but possesses a series of dark vertical bars on the anterior portion of the flanks, though these are apparently indistinct in juveniles and some females.

In recent years it’s become commonplace to refer to the stripes on the body and fins of danionins as follows:

– P stripe: or ‘pigment stripe‘ is the central, dark, lateral stripe on the body which extends into the caudal-fin in some species. Stripes above it are numbered P+1, P+2, etc., and those beneath P-1, P-2, P-3.
– A stripe: the central stripe on the anal-fin; the proximal stripe (above it) is A+1 and the distal stripe (beneath) A-1.
– D stripe: The submarginal dorsal-fin stripe.

Following Fang (2003) Devario spp. are characterised by: possession of a P stripe extending onto the median caudal-fin rays; a short maxillary barbel (absent in some species); absence of the A stripe (a less distinct, relatively wide stripe is present in some species, e.g., D. acrostomus, D. annandalei, D. xyrops); a short, wide premaxillary process (cleft in the upper jaw) with a tiny apophysis (bony tubercule) touching the kinethmoid bone; infraorbital 5 not or slightly reduced.

The current genus name has only been in general use since 2003 prior to which members were considered to belong to the genus Danio.

Older, molecular, phylogenies tended to agree that the latter represented a monophyletic group consisting of two major clades; the ‘Danio devario‘ grouping containing the larger, deeper-bodied species and the ‘D. rerio‘ assemblage comprising the smaller, slimmer fish.

The currently invalid genus name ‘Brachydanio‘ was often adopted for members of the latter group and is seen in much of the older aquarium literature.

However in 2003 Fang Fang conducted a more detailed study based on morphological characters which included members of other related genera, and the results suggested for the first time that the genus Danio as previously considered represents a polyphyletic grouping.

The genus name Devario was suggested for the larger species with Danio being applied only to the smaller fish, although following Kottelat (2013) the latter should be used only for the type species, Danio dangila, with most former members placed within the revalidated genera Brachydanio and Celestichthys.

These results have largely been supported by subsequent phylogenetic analyses (e.g. Mayden et al., 2007), although Devario has still undergone a little reshuffling, particularly following Fang et al. (2009) and Kottelat (2013).

In the former study the two species previously comprising the genus Inlecypris were brought into synonymy with Devario and three species formerly included in Microrasbora were moved into the new genus Microdevario based on possession of shared synapomorphies with Devario. The existence of a monophyletic clade consisting of the genera Devario, Chela, Laubuca, Microdevario and Microrasbora was also hypothesised, a theory upheld in the more recent study by Tang et al. (2010). The genus Betadevario (Pramod et al., 2010) is also nested within this grouping and is sister to Devario and Microrasbora.

Kottelat (2013) revalidated the genus Inlecypris whilst noting that phylogenetic evidence suggests the existence of two genetic lineages within Devario. The first contains the species with prominent lateral stripes, which leaves the remaining members (D. apogon and D. chrysotaeniatus) of uncertain taxonomic placement. In addition, a number of the striped species share a colour pattern comprising a midlateral stripe on the posterior half of the body with a few bars in the anterior portion and golden patches between them. These may eventually be placed in a separate genus for which the name Parabarilius is available.

References

1. Hora, S. L., 1921 - Records of the Indian Museum (Calcutta) 22(pt 3, no. 19): 165-214
   Fish and fisheries of Manipur with some observations on those of the Naga Hills.
2. Fang, F., 2003 - Copeia 2003(4): 714-728
   Phylogenetic Analysis of the Asian Cyprinid Genus Danio (Teleostei, Cyprinidae).
3. Fang, F., 2000 - Ichthyological Research 47(1): 13-26
   Barred Danio species from the Irrawaddy River drainage (Teleostei, Cyprinidae).
4. Fang, F., M. Norén, T. Y. Liao, M. Källersjö and S. O. Kullander, 2009 - Zoologica Scripta 38(1): 1-20
   Molecular phylogenetic interrelationships of the south Asian cyprinid genera Danio, Devario and Microrasbora (Teleostei, Cyprinidae, Danioninae).
5. Kottelat, M., 2013 - The Raffles Bulletin of Zoology Supplement 27: 1-663
   The fishes of the inland waters of southeast Asia: a catalogue and core bibiography of the fishes known to occur in freshwaters, mangroves and estuaries.
6. Mayden, R. L., K. L. Tang, K. W. Conway, J. Freyhof, S. Chamberlain, M. Haskins, L. Schneider, M. Sudkamp, R. M. Wood, M. Agnew, A. Bufalino, Z. Sulaiman, M. Miya, K. Saitoh, S. He, 2007 - Journal of Experimental Zoology, Molecular Development and Evolution 308B: 642–654
   Phylogenetic relationships of Danio within the order Cypriniformes: a framework for comparative and evolutionary studies of a model species.
7. Pramod, P. K., F. Fang, K. Rema Devi, T.-Y. Liao, T. J. Indra, K. S. Jameela Beevi and S. O. Kullander, 2010 - Zootaxa 2519: 31-47
   Betadevario ramachandrani a new danionine genus and species from the Western Ghats of India (Teleostei: Cyprinidae: Danioninae).
8. Sen, N., 2007 - Records of the Zoological Survey of India 107(4): 27-31
   Description of a new species of Brachydanio Weber and de Beaufort, 1916 (Pisces: Cypriniformes: Cyprinidae) from Meghalaya, north east India with a note on comparative studies of other known species.
9. 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).
10. Vishwanath, W., M. Wahengbam, L. Kosygin and K. S. Selim, 1998 - Italian Journal of Zoology 65, Supplement 1: 321-324
    Biodiversity of freshwater fishes of Manipur, India.