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Danio choprae HORA, 1928

Glowlight Danio

SynonymsTop ↑

Brachydanio choprai (Hora, 1928); Danio choprai Hora, 1928

Etymology

Danio: from Dhani, a Bengalese vernacular term for small, minnow-like cyprinids.

choprae: named for Dr. B. N. Chopra, who collected the original specimens (see ‘Notes’ for information on spelling).

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

The type specimens were collected from ‘small rocky streams’ of the  Mogaung Chaung river system close to the towns of ‘Kamaing’ (often referred to as Kar Maing) and Namma (Nanmati?)in Myitkyina District, Kachin State, northern Myanmar, and the species appears restricted to this tributary of the much larger Ayeyarwaddy drainage.

It’s being bred on a commercial basis so you might find wild caught specimens hard to come by in the aquarium hobby, though.

Specimens from a population of similar-looking fish from the area around Thandwe in Rakhine State on Myanmar’s western coast that were initially misidentified as D. choprae by Hora (1937) were collected in 1998 by Kullander and Britz and eventually described as D. aesculapii by Kullander and Fang (2009).

A third species from the mountainous region of Putao in the far north of Kachin was described as D. flagrans by Kullander (2012).

Myanmar can be considered a centre of diversity for the genus with over ten species, most of which are endemic to the country.

Habitat

This species shows a preference for small hill streams with substrates of gravel and variably-sized rocks. On habitat comprised a larger pool with muddy substrate, no aquatic plants and clear water.

This was located at the foot of a hill and measured around 30 m across and 30-50 cm deep.

An outflow described as a ‘small trickle’, just 30 cm wide and 20 cm deep, emerged from the pool and meandered through surrounding grassland.

Water temperature was 24.8°C/76.6°F, pH 7.6 and conductivity 11 μS · cm−1 (Kullander, 2012).

Maximum Standard Length

One of the smaller members of the genus reaching 25 – 30 mm.

Aquarium SizeTop ↑

Base dimensions of 80 ∗ 30 cm or larger are required for this active species.

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 as small Danio spp. such as this 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:16 – 26 °C

pH6.0 – 8.0

Hardness18 – 215 ppm

Diet

Almost certain to prey chiefly on insects and their larvae in nature. 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 ↑

Generally very peaceful making it an ideal resident of the well-furnished community tank.

Since it places no special demands in terms of water chemistry it can be combined with many of the most popular fish in the hobby including other small cyprinids as well as tetras, livebearers, rainbowfish, anabantoids, catfish and loaches.

A community based around stream-dwelling species from the Irrawaddy/Ayeyarwady basin would also make an interesting project with possibilities including Badis kyar, Acanthocobitis botia, Botia histrionica, B. rostrata, Lepidocephalichthys berdmorei, Schistura vinciguerrae, Crossocheilus latius, Danio albolineatus, Pethia didi, P. erythromycter, P. stoliczkanus, P. ticto, Devario apogon, D. shanensis, and Rasbora daniconius among others.

It’s a schooling species by nature and really should be kept in a group of at least 8-10 specimens which will develop a pecking order among themselves.

Maintaining it in decent numbers will therefore not only help make the fish less nervous but will allow sub-dominant fish of both sexes some respite from the alpha male(s) which can be quite aggressive at times.

It’s not uncommon to see nipped fins in lesser individuals within a group though this behaviour does not normally extend to tankmates.

Sexual Dimorphism

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

The differences are especially clear when the fish are in spawning condition as the males intensify in colour and females fill with eggs.

Reproduction

Like many small cyprinids this species is an egg-scattering spawner that exhibits no parental care.

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

However if you want to increase the yield of fry a slightly more controlled approach is required.

The adult group can still be conditioned together but one or more smaller, say 10-15 litre, containers should also be set up and half-filled with water.

These 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 it but small enough so that the adults cannot reach them.

The widely available plastic ‘grass’-type matting can also be used and works very well; alternatively filling much of the tank with Java moss or other fine-leaved plant can also yield good results.

The water itself should be of slightly acidic to neutral pH with a temperature towards the upper end of the range suggested above.

A small 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.

The pair should spawn the following morning. The easiest and quickest way to tell is simply to look at the female since if the fish have spawned she will be noticeably slimmer.

The adults will eat any eggs they find and are best removed after a couple of days at which point the power filter should be switched for a mature sponge-type unit in order to avoid fry being sucked into the mechanism.

Incubation is temperature-dependant to an extent but usually takes around 72 hours with the young free-swimming a couple of days later.

Initial food should be Paramecium or or a proprietary dry food of sufficiently small (5-50 micron diameter) grade, introducing Artemia nauplii, microworm, etc., once the fry are large enough to accept them.

NotesTop ↑

D. choprae has been available in the aquarium trade since around 2003 but has quickly established itself as one of the most popular small danios in the hobby.

There has been some confusion regarding the correct spelling of the specific name with it sometimes spelled ‘choprai but this is cleared up by Kullander (2012).

Briefly, when Hora described the species he named it after the collector, Dr B. N. Chopra, but in 1937 changed this to ‘choprai‘ stating that the original spelling had been an error.

This would imply that Dr. Chopra was male although Hora does not explicitly say so in either paper, and at any rate the ICZN dictates that amendment of the original name is not allowed in such cases, hence Danio choprae is the accepted combination.

In addition, should Chopra be considered a latinised name the natural spelling would be Choprae regardless of the name-bearer’s gender.

It appears very similar to D. flagrans and these two are distinguished from other danios by their shared colour pattern consisting of several vertical  bars on the flanks, followed by postabdominal P and P+1 stripes, a distinct P+2 stripe anterior to the dorsal-fin, and red stripes between the middorsal and P+2 stripes, and between the P and P+1 stripes. Both also possess well-developed tubercles on the infraorbital ossicles.

 It can be told apart from D. flagrans by the following characters: body deeper (26.6-31.6 % SL vs. 22.5-26.6 % SL in D. flagrans); caudal peduncle shorter (16.1-19.1 % SL vs. 20.5-24.7 % SL); base of anal-fin longer (19.2-23.9 % SL vs. 14.2-18.3 % SL); rostral barbels shorter (5.9-10.1 % SL vs. 10.3-18.7 % SL), not reaching posterior margin of orbit in adults (vs. reaching beyond preopercular margin); maxillary barbels shorter, not reaching to base of pectoral-fin in adults (vs. reaching to below base of pectoral-fin), lateral line almost always absent, occasionally up to three perforated scales(vs. almost always present, up to seven perforated scales), fewer vertebrae contained in caudal peduncle (6-8 vs. 9-10); 12½-13½, rarely 11½, branched anal-fin rays (vs. 9½-11½); base of anal-fin dark (vs. hyaline); black streak in lower lobe of caudal-fin usually present (vs. absent).

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) Danio 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.

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 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) have resulted in further changes.

Unfortunately while these works agree in some aspects they frequently contradict each other, notably in the usage of the subfamily names Rasborinae (Weber and de Baeufort, 1916) and Danioninae (Bleeker, 1863), the positioning of D. kyathit in relation to D. rerio and the degree of relatedness between Danio and Esomus species.

The species formerly known as Microrasbora erythromicron was found to be grouped within Danio in both sets of results.

At present SF follows the results of Fang et al. (2009), thus Danio is considered to be composed of three sub-clades, i.e., groupings of closely-related species.

The first comprises D. erythromicron, D. margaritatus, D. choprae and D. flagrans.

These exhibit unique body patterning consisting of vertical bars (D. erythromicron, D. choprae, D. flagrans) or light spots (D. margaritatus) and possess either very short barbels or none at all, whereas all other Danio spp. have lateral or horizontal stripes on the body and relatively long barbels.

There’s a suggestion that D. erythromicron and D. margaritatus will be moved again in the future as the two share morphological and behavioural aspects that appear to set them apart from other danios.

The second clade contains 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 D. dangila group is also likely to contain D. meghayalensis and D. feegradei.

The remaining species, of which D. rerio is thought to be the most ancient, are included in the third sub-clade, and there is a possibility these three groups may eventually be separated into different genera.

References

  1. 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.
  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. Kullander, S. O., 2012 - Ichthyological Exploration of Freshwaters 23(3): 245-262
    Description of Danio flagrans, and redescription of D. choprae, two closely related species from the Ayeyarwaddy River drainage in northern Myanmar (Teleostei: Cyprinidae).
  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.

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