Chagunius chagunio
SynonymsTop ↑
Cyprinus chagunio Hamilton, 1822; Barbus spilopholus McClelland, 1839; Barbus beavani Günther, 1868
Etymology
Chagunius: from Chaguni, the vernacular Bengali name for this species.
chagunio: as above.
Classification
Order: Cypriniformes Family: Cyprinidae
Distribution
Endemic to the Ganges and Brahmaputra river basins and thus occurs in northern India, Nepal and Bangladesh. Type locality is ‘the Yamuna River, and northern rivers of Behar and Bengal’.
The distribution of the genus as a whole is interesting because these fish occupy the area that geographically separates Indian and Southeast Asia barbs and it has been theorised that they may represent an evolutionary ‘link’ species (Rainboth, 1986). They also exhibit an intriguing morphology that can be described as intermediate between Indian Hypselobarbus and Southeast Asian genera such as Tor in some respects.
Habitat
Chagunius species inhabit highland rivers and tributaries containing clear water and substrates of rock, gravel and/or sand. They have been recorded in areas of rapids as well as sections with moderate current and patches of aquatic vegetation.
Rainboth noted that even juveniles are found in the main channels, as opposed to backwater habitats, but they show a preference for slightly calmer water than adults. The latter can often be found schooling with Tor spp. in faster-flowing zones.
Maximum Standard Length
400 – 450 mm.
Aquarium SizeTop ↑
While juveniles can be grown on in smaller quarters even a single fully-grown specimen would require an aquarium with base dimensions of 240 ∗ 90 cm, and it can only be considered suitable for public aquaria plus a very small minority of private aquarists
Maintenance
Choice of décor is not likely to be as critical as water quality and the amount of open swimming-space provided. However should you possess the means to both provide and decorate a sufficiently-sized tank for long term care this species would look superb in a set-up designed to resemble a flowing river with a substrate of variably-sized rocks and gravel, some large water-worn boulders and perhaps a couple of driftwood branches.
Like many other species that hail from running waters it’s almost certain to react poorly to any accumulation of organic wastes and spotless water will be required in order for it to thrive. There should also be a high level of dissolved oxygen and a decent amount of water movement in the tank. A large external-style filter or two are going to be needed in order to provide the desired levels of oxygen, flow and surface area for bacterial colonisation. Be sure to fit the tank with a heavy, tightly-fitting cover as larger cyprinids can be quite skittish at times and usually possess a powerful leap.
Water Conditions
Temperature: 20 – 25 °C
pH: 6.0 – 7.5
Hardness: 36 – 357 ppm
Diet
Stomach analyses of wild specimens revealed the diet to be composed of insect larvae and aquatic gastropods. Plant material did not appear to be consumed in large quantities and members of the genus are prehaps best described as foraging micropredators.
For it to develop its best condition it should therefore be offered regular meals of small live and frozen foods such as bloodworm, Daphnia and Artemia along with good quality dried flakes and granules.
Behaviour and CompatibilityTop ↑
C. chagunio is unlikely to prey on tankmates although its adult size dictates that very small species are best omitted. Fish that inhabit similar environments in nature such as many cyprinids and loaches should make the best companions but as we believe it is generally unsuitable for the home aquarium to provide a more detailed list of suggestions would seem imprudent.
This species is found swimming in loose aggregations in nature and might exhibit shy or skittish behaviour if kept singly or in small numbers. It’s likely to be a shoaling rather than schooling fish which develops a distinct pecking order and we therefore recommend purchasing a group of six or more if you are lucky enough to find it on sale in such numbers.
This will provide a more natural-looking display plus interesting behaviour from the fish as they interact with conspecifics. It goes without saying that the size of aquarium required to adequately accommodate such a community over anything other than the short term is beyond the reach of most hobbyists.
Sexual Dimorphism
It is impossible to accurately sex young fish by external characters but males develop noticeable tubercules on the head and extensions to the last two anal fin rays as they mature.
Reproduction
As far as we know it has not been bred in captivity.
NotesTop ↑
Chagunius spp. are rarely-kept in aquaria, only occasionally showing up as bycatch among shipments of wild fishes from India, Myanmar, and Thailand. While C. chagunio grows too large to be considerd suitable for the majority of home aquaria, the smaller and more manageable C. baileyi is available from time-to-time.
There are currently three species in the genus which look almost identical at first glance. They are most easily separated by collection details since their ranges do not overlap in nature; C. baileyi is endemic to the Salween drainage and C. nicholsi to the Ayeyarwady.
Morphological differences are only minor, with C. chagunio possessing more circumferential scales (40, vs. 36 or less) and more circumpeduncular scales (23-25, vs. 18-20) than the other two. C. baileyi and C. nicholsi can only be told apart by counting the anal scales (4-5 in the former, vs. 2) and the relative size of the eye (slightly larger in C. baileyi). We’re yet to see images of live C. nicholsi but a further distinguishing characteristic between young C. baileyi and C. chagunio is the presence of red marginal stripes in the caudal fin of the former, though apparently this colouration is lost as the fish mature.
References
- Hamilton, F., 1822 - Edinburgh & London: i-vii + 1-405
An account of the fishes found in the river Ganges and its branches. - Rainboth, W. J., 1986 - Occasional Papers of the Museum of Zoology University of Michigan 712: 1-17
Fishes of the Asian Cyprinid Genus Chagunius.
