Cyprinus dangila Hamilton, 1822; Danio deyi Sen, 1985; Perilampus reticulatus McClelland, 1839
Said to be found throughout the Ganges River basin although most records we’ve been able to find from India and Bangladesh correspond to the Brahmaputra drainage.
The type specimens were apparently collected from the district of Munger, Bihar State, India through which the main Ganges channel flows, although all have since been lost.
It’s also been reported from tributaries of the Brahmaputra in Bhutan and, more recently, from Myanmar where it appears to be quite widely distributed as some collections occurred as far south as the state of Mon. Based on images it seems the fish can vary considerably in patterning depending on locality.
The type series was collected from ‘mountain streams’ but the only confirmed habitat image we’ve seen depicts a sluggish, swampy environment with dense marginal vegetation. Given its extensive natural range it would seem this species is adaptable and able to colonise various habitat types.
In the Barak River drainage, which flows through the north-east Indian states of Nagaland and Assam before bifurcating at the Bangladesh border, symaptric species include Barilius barna, B. bendelisis, B. dogarsinghi, Laubuca laubuca, Esomus danricus, Devario aequipinnatus, D. annandalei, D. devario, Rasbora daniconius, R. rasbora, Crossocheilus latius, Garra gotyla, G. lissorhynchus, G. nasuta, Balitora brucei, Acanthocobitis botia, Botia rostrata and Lepidocephalichthys guntea.
Maximum Standard Length
One of the largest danios reaching 120 – 130 mm.
Aquarium SizeTop ↑
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 should you wish.
Since it naturally occurs in pristine habitats it’s intolerant to accumulation of organic pollutants and requires 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 decent water movement so a good-sized external filter or powerhead(s) should be employed as necessary and weekly water changes of 30-50% aquarium volume considered routine.
Temperature: 16 – 24 °C
pH: Weakly acidic to neutral water within the range 6.5 – 7.5 is usually recommended.
Hardness: 36 – 268 ppm
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 ↑
Not an aggressive fish but may upset very slow-moving or timid tankmates with its constant activity and vigorous feeding behaviour so can only be considered appropriate for larger tanks containing robust, similarly-sized fishes.
There are plenty of suitable choices including many cyprinids, loaches, cichlids, catfishes and characins although as always when selecting a compatible community of fish proper research is essential.
It’s a schooling species by nature and ideally should be kept in a group of at least 8-10 specimens. Maintaining it in decent numbers will not only make the fish less prone to bouts of skittishness but will result in a more effective, natural looking display. Any aggressiveness will normally also be contained as the fish concentrate on maintaining their hierarchical position within the group.
Sexually mature females are usually rounder-bellied and exhibit a white stripe towards the distal edge of the anal-fin which is red in males. The differences are especially clear when the fish are in spawning condition as the males intensify in colour and the females fill with eggs.
Like many cyprinids this species is an egg-scatterer that exhibits no parental care. However it seems to be one of the trickier danios to spawn in captivity as we have struggled to find reliable information so far, even by word of mouth.
The only report of a success we know of involved two fully-grown adult pairs which were added to a very large, 283 litre, ‘container’.
Plenty of water movement was provided and the base filled with fine-leaved plants to act as a spawning medium. A mixture of live and frozen foods were used to condition the fish and ‘a couple of thousand’ fry were successfully raised.
The vernacular name refers to the fact this species possesses exceptionally long barbels. Considering its apparent abundance in nature it remains uncommon in the hobby and little is written regarding its captive care.
D. meghalayensis, formerly considered synonymous, is now considered a distinct species and is similar-looking but has a predominantly striped, as opposed to spotted, patterning on the body and a greater proportion of red colouration in the fins.
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 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.
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 level 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., 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.
- 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.
- Fang, F., 2003 - Copeia 2003(4): 714-728
Phylogenetic Analysis of the Asian Cyprinid Genus Danio (Teleostei, Cyprinidae).
- 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).
- Kar, D. and N. Sen, 2007 - Zoo's Print Journal 22(3): 2599-2607
Systematic List and Distribution of Fishes in Mizoram, Tripura and Barak Drainage of Northeastern India.
- 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.