Parabarilius laoensis Pellegrin & Fang, 1940; Danio laoensis (Pellegrin & Fang, 1940); Daniops myersi Smith, 1945; Danio myersi (Smith, 1945)
Named for the country of Laos.
Described from ‘Ban Nam Khueng’, northwestern Laos and since recorded from various localities within the upper Mekong watershed in Laos and Thailand (Chiang Rai and possibly Chiang Mai provinces).
Rainboth (1996) reported it to occur in the Salween River which borders western Thailand for a stretch but no other records from that drainage exist as far as we know.
This species‘ habitats are situated at relatively high altitude and receive a great deal of rainfall between the months of May and October. It’s likely to be restricted to hill streams and small rivers with substrates of gravel/variably-sized rocks and some marginal or over-hanging vegetation. Water flow is almost certainly variable depending on time of year.
In the River Nam Mae Lao, Chiang Rai province, northern Thailand D. laoensis was collected alongside Danio roseus. It’s also been recorded downstream of the Kuang Si (also spelled Kuang Xi) Falls in Luang Prabang Province, northern Laos.
This series of multi-tiered, travertinous falls, cascades and pools flows over a forested limestone cliff and the water is tinted a bright blue/green colour due to reflection of light from the high levels of calcium carbonate it contains. The loach Schistura sertata was collected at the same locality.
A further collection locality was a small stream in Phôngsali Province, northern Laos located within the Nam Ou river watershed. There it occurred sympatrically with Acheilognathus deignani, Cyprinus rubrofuscus, Mystacoleucus greenwayi, Pseudorasbora parva, and ‘Puntius’ semifasciolatus.
Maximum Standard Length
55 – 65 mm would seem likely.
Aquarium SizeTop ↑
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 environment resembling 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 likely intolerant to accumulation of organic pollutants and requires more-or-less 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 moderate water movement.
Temperature: 23 – 26 °C
pH: 6.0 – 7.5
Hardness: 18 – 179 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 ↑
Probably not an aggressive fish but may upset slow-moving or timid tankmates with its constant activity and vigorous feeding behaviour so is most appropriate for larger 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. Maintaining it in decent numbers will not only make the fish less nervous but will result in a more effective, natural looking display. 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.
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.
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. 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, signified by the female appearing noticeably slimmer. After 48 hours the adults should be removed whether spawning has occurred 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.
This species is more-or-less unheard of in the hobby at time of writing, though a handful specimens were imported to Singapore in the late 2000s. It has a complete lateral line, well-developed infraorbital process, 8-9 branched dorsal-fin rays, 12-14 branched anal-fin rays and two rows of pharyngeal teeth.
It can be further distinguished from other species in the genus by colour pattern consisting of a dark, horizontal P stripe originating around mid-body, where it’s relatively faint, this becoming thicker and darker in the posterior portion of the body and terminating at the base of the caudal-fin.
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‘ grouping containing the larger, deeper-bodied species and the ‘D. rerio’ assemblage 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.
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). In that 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.
Within the family Cyprinidae the ‘Devario clade’ is most closely-related to a ‘Danio clade’ containing the genera Danio and Danionella plus an ‘Esomus clade’ which groups Esomus alongside Paedocypris and Sundadanio. Closer relationships within Devario itself require further research, however.
- Fang, F., 2003 - Copeia 2003(4): 714-728
Phylogenetic Analysis of the Asian Cyprinid Genus Danio (Teleostei, Cyprinidae).
- Fang, F. and M. Kottelat, 1999 - Ichthyological Exploration of Freshwaters 10(3): 281-295
Danio species from northern Laos, with descriptions of three new species (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).
- Kottelat, M., 2009 - WWF – Comfish Project Report: 1-27
Fishes of the upper Nam Ou drainage in Laos
- Kottelat, M., 2001 - WHT Publications Ltd., Colombo 5, Sri Lanka: 1-198
Fishes of Laos.
- Kottelat, M., 1998 - Ichthyological Exploration of Freshwaters 9(1): 1-128
Fishes of the Nam Theun and Xe Bangfai basins, Laos, with diagnoses of twenty-two new species (Teleostei: Cyprinidae, Balitoridae, Cobitidae, Coiidae and Odontobutidae).
- 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.
- 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).
- 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).