Devario interruptus (DAY, 1870)

SynonymsTop ↑

Barilius interrupta Day, 1870; Danio interruptus (Day, 1870); Danio interrupta (Day, 1870)

Etymology

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

interruptus: from the Latin interruptus, meaning ‘broken apart, interrupted’, presumably in reference to this species’ incomplete lateral line.

Classification

Order: Cypriniformes Family: Cyprinidae

Distribution

Type locality is ‘Hotha, Yunnan Province, China’ which corresponds to the Hotha/Husa valley in Longchuan County, Dehong Prefecture, Yunnan province, southwestern China and appears endemic to the area with subsequent occurrence records from neighbouring Longling County (Baoshan Prefecture) and municipality of Ruili City.

All known localities are within the region bordering Myanmar and part of the upper Ayeyarwady/Irrawaddy River watershed.

Habitat

This species has mostly been collected from small (1-2 metres wide, 20-40 cm deep), moderate-to-swiftly-flowing streams with clear water, substrates of sand, gravel and rocks and no aquatic vegetation.

Marginal vegetation was present in some cases, offering a degree of shade, and sympatric species included an unidentified Schistura sp., S. vinciguerrae, Misgurnus anguillicaudatus, Garra qiaojiensis, Exostoma labiatum, E. vinciguerrae and Oreoglanis macropterus.

Some parts of its range are cultivated and in one case it was collected from a fast-flowing, man-made irrigation channel with quite turbid water and a mixed substrate composed of sand, clay and debris.

The only other species found was Brachydanio albolineata and in all cases habitats were relatively at high altitudes between 750-1500 metres AMSL.

Maximum Standard Length

55 – 60 mm.

Aquarium SizeTop ↑

An aquarium with surface dimensions of 75 ∗ 30 cm or similar should be the smallest considered.

Maintenance

No information regarding captive care exists but presumably it won’t prove difficult to keep in a well-maintained set-up as with related species.

It’s likely to thrive in an aquarium set up 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 probably intolerant to accumulation of organic pollutants and requires more-or-less spotless water in order to thrive.

Though very fast flow is unnecessary it should also prefer 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: Average air temperatures in Baoshan Prefecture range from 48.2 – 70.7°F/9 – 21.5°C so this species is likely to prefer cooler conditions between 16 – 21 °C.

pH: 6.5 – 7.5

Hardness: 36 – 179 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 ↑

Probably not an aggressive fish but may intimidate slow-moving or timid tankmates with its constant activity and vigorous feeding behaviour, meaning it’s probably most appropriate for aquaria containing robust, similarly-sized fishes.

There are plenty of suitable choices including many cyprinids, loaches, cichlids, catfish 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 which will not only make the fish less nervous but result in a more effective, natural looking display.

Based on experience with congeners any aggression will also be contained as the fish concentrate on maintaining their hierarchical position within the group, and males tend to display better colours in the presence of rivals.

Sexual Dimorphism

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

When in breeding condition the lower half of the body is suffused with bright orange in dominant male specimens.

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 more-or-less unheard of in the aquarium hobby at time of writing and has yet to be exported as far as we know.

It’s distinguishable from similar-looking congeners by a combination of characters as follows: lateral line incomplete with 7-17 pored scales; infraorbital process absent; 7-8 branched dorsal-fin rays; usually 10-11 branched anal-fin rays; flank markings consisting of a series of short, relatively wide and equally deep vertical bars/blotches which are slightly wider than the P stripe; P stripe consisting of a row of contiguous dark blotches and terminating at base of caudal-fin; cleithral spot present; no barbels.

It’s most easily confused with D. maetaengensis and D. shanensis but in D. shanensis the lateral line is complete or incomplete with 23-25 pored scales, rudimentary maxillary barbels may be present, and the flank markings comprise a series of vertical bars which become gradually deeper, then gradually shorter, with the most posterior the same depth as the P stripe. The P stripe itself is uniformly-pigmented.

In D. maetaengensis the lateral line is complete with 31-35 pored scales, both rostral and maxillary barbels are present, and the flank markings are comparable to D. shanensis except the P stripe which consists of a series of contiguous blotches.

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‘ group containing the larger, deeper-bodied species and the ‘D. rerio‘ clade comprising the smaller, slimmer fish.

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.

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. Day, F., 1870 - Proceedings of the General Meetings for Scientific Business of the Zoological Society of London 1869(3): 548-560
   Remarks on some fishes in the Calcutta Museum - Part II.
2. Fang, F., 1997 - Ichthyological Exploration of Freshwaters 8(1): 41-48
   Danio maetaengensis, a new species of cyprinid fish from northern Thailand.
3. Fang, F., 2000 - Ichthyological Research 47(1): 13-26
   Barred Danio species from the Irrawaddy River drainage (Teleostei, Cyprinidae).
4. Fang, F., 2003 - Copeia 2003(4): 714-728
   Phylogenetic Analysis of the Asian Cyprinid Genus Danio (Teleostei, Cyprinidae).
5. 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).
6. 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.
7. 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 - Phylogenetic relationships of Danio within the order Cypriniformes: a framework for comparative and evolutionary studies of a model species.: 642–654
   Phylogenetic relationships of Danio within the order Cypriniformes: a framework for comparative and evolutionary studies of a model species.
8. 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).
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).