Brachydanio jaintianensis (SEN, 2007)

SynonymsTop ↑

Danio jaintianensis (Sen, 2007)

Etymology

Brachydanio: from the Ancient Greek βραχύς (brakhús), meaning ‘short’, and Dhani, a Bengalese vernacular term for small, minnow-like cyprinids.

jaintianensis: named for the Jaintia Hills district from where the type series was collected.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

To date known only from the Jaintia Hills district, Meghalaya state, northeastern India meaning its natural waters are part of the Brahmaputra River system.

The type locality is given as ‘Tre Rangriang, Jowai’ in the description paper, but we’ve been unable to locate this on any map.

The paratypes were collected at ‘Thlu Muwi’, which probably refers to the ancient stone bridge built over the Muwi stream, a place popular with tourists due to the nearby Muwi waterfalls.

Habitat

Much of Meghalaya consists of forested hills which receive a great deal of rainfall and many of its high-elevation waters flow very swiftly, but this species is likely to be restricted to small, slower-moving hill streams with substrates of gravel/variably-sized rocks and well-developed marginal or over-hanging vegetation.

Maximum Standard Length

Reports suggest 40 – 45 mm.

Aquarium SizeTop ↑

An aquarium with base measurements of 80 ∗ 30 cm or equivalent is large enough to house a group.

Maintenance

Looks particularly effective in a heavily-planted arrangement with a darker substrate, and may appear paler in sparsely-decorated set-ups.

We suggest maintaining it in a well-planted aquarium or set-up designed to resemble a flowing river or stream, with a substrate of variably-sized rocks and gravel and some large water-worn boulders.

Additional powerhead(s) or filter outlets can be used to provide flow but torrent-like conditions should be avoided since small danionins tend to occupy calmer stretches and marginal zones in nature.

Driftwood roots, branches and aquatic plants, with hardy genera such as Microsorum, Bolbitis or Anubias ideal since they can be grown attached to the décor, can also be added.

The aquarium must have a very tightly-fitting cover as members of this genus are accomplished jumpers and can fit through surprisingly small gaps.

Water Conditions

Temperature: Air temperatures in Meghalaya vary from sub-zero in winter to around 73.4°F/23°C in summer so it’s best kept in an unheated tank and tends to struggle if maintained above 77°F/25°C for extended periods. 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. In the aquarium it’s largely an unfussy feeder and will accept most foods.

A good quality dried product or two 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 fish to show the best colouration and conditioning.

Behaviour and CompatibilityTop ↑

This species is peaceful but its temperature requirements and rarity make it difficult to recommend for the general community.

It’s best kept in a species display or alongside other small cyprinids that appreciate cooler conditions.

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

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

Suitable options from Meghalaya, though not necessarily occurring sympatrically, include Brachydanio rerio, Pethia shalynius, Lepidocephalichthys guntea and Acanthocobitis botia.

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 result in a more effective, natural-looking display while males will also exhibit 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

We know of no reports as yet but like other danionins this species should be an egg-scattering spawner that exhibits no parental care.

That’s to say when the fish are in good condition they’re likely to spawn often and in a densely-planted, mature aquarium it’s possible that small numbers of fry may start to appear without intervention.

However if you want to increase the yield of fry a slightly more controlled approach is required, and the following method has proven successful for other members of the genus.

The adult group can still be conditioned together but one or more separate containers should also be set up and half-filled with water.

Much of the available space should be filled with a suitable spawning medium such as Java moss, wool mops or a spawning grid.

The water 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, or by performing a large (50-60%) water change in the evening.

Several spawning events will probably occur before a female is spent of eggs.

The adults will eat any they find and are best removed once eggs are spotted.

At this point the power filter (if using) should be switched for a mature sponge-type unit in order to avoid fry being sucked into the mechanism.

Incubation in is temperature-dependant to an extent but usually takes between 24-36 hours with the young free-swimming a few days later.

Initial food should be of an infusoria-type grade followed by Artemia nauplii, microworm or similar.

NotesTop ↑

This species has occasionally been available in the aquarium trade since its discovery.

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) Brachydanio spp. are characterised by the presence of an A stripe on the anal-fin and two or more P stripes on the caudal, plus some internal characteristics such as enlarged nasal lamellae.

The genus has undergone some significant taxonomic reshuffling in recent years following the publication of a series of phylogenetic studies.

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

However in 2003 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, i.e., not all members derived from a single common ancestor.

The genus name Devario was suggested for the larger species with Danio being applied only to the smaller fish (with the exception of the type species, D. dangila which can grow to around 89 mm SL). Recent molecular studies by Mayden et al. (2007) and Fang et al. (2009) resulted in further changes, with the latter study considering the genus Danio to be composed of three subclades. These were subsequently split into distinct genera by Kottelat (2013), as follows:

The former species D. erythromicron, D. margaritatus, D. choprae and D. flagrans are grouped together in the revalidated genus Celestichthys Roberts, 2007. These exhibit unique body patterning consisting of vertical bars (C. erythromicron, C. choprae, C. flagrans) or light spots (C. margaritatus) and possess either very short barbels or none at all.

The genus Danio contains only the type species, D. dangila, separated on the basis of its larger size and the shape of the caudal-fin, which in adults is only slightly emarginate or even truncate in shape, a feature it shares only with Tinca tinca (the common tench) among other cyprinids.

The remaining species, of which B. rerio is thought to be the most ancient, are included in the revalidated genus Brachydanio Weber & de Beaufort, 1916.

References

1. 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.
2. Conway, K. W., W.-J. Chen and R. L. Mayden, 2008 - Zootaxa 1686: 1-28
   The 'Celestial Pearl danio' is a miniature Danio (s.s) (Ostariophysi: Cyprinidae): evidence from morphology and molecules.
3. Fang, F., 2003 - Copeia 2003(4): 714-728
   Phylogenetic Analysis of the Asian Cyprinid Genus Danio (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. Kullander, S. O. and F. Fang, 2009 - Zootaxa 2164: 41-48
   Danio aesculapii, a new species of danio from south-western Myanmar (Teleostei: Cyprinidae).
7. Kullander, S. O., T. Y. Liao and F. Fang, 2009 - Ichthyological Exploration of Freshwaters 20(3): 193-199
   Danio quagga, a new species of striped danio from western Myanmar (Teleostei: Cyprinidae).
8. 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.
9. Roberts, T. R., 2007 - Raffles Bulletin of Zoology 55(1): 131-140
   The 'Celestial Pearl Danio', a new genus and species of colourful minute cyprinid fish from Myanmar (Pisces: Cypriniformes).