Laubuka laubuca

Laubuka: from Layubuka, a vernacular Bengali name for L. laubuca, the type species of the genus.

laubuca: as above.

Probably endemic to northern India, Bangladesh, and Nepal. Records from Sri Lanka, southern India, Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, and Indonesia appear to represent other species (see 'Notes').

Type locality is 'ponds of the northern parts of Bengal'.

Inhabits small tributary streams, freshwater pools, canals, rice paddies and other quiet water bodies. It is invariably observed swimming in groups at or just below the water surface.

An aquarium with base dimensions of 120 ∗ 30 cm48 ∗ 12 in or equivalent should be the smallest considered.

This species will do well in most well-maintained larger aquaria but is best maintained in a set-up designed to resemble a slowly-flowing river or stream, with a substrate of variably-sized rocks, gravel and some large water-worn boulders.

This can be further furnished with driftwood branches, and aquatic plants such as Microsorum, Bolbitis or Anubias spp. can be grown attached to the décor. In this kind of environment it will display more natural behaviour and can be kept alongside other species that enjoy similar conditions.

Like many fishes that naturally inhabit running waters it’s intolerant to the accumulation of organic wastes and requires spotless water at all times in order to thrive. The aquarium must also have a tightly-fitting cover since this species is an accomplished jumper.

Naturally a surface feeder preying on terrestrial and aquatic invertebrates. In the aquarium it will accept dried foods of a suitable size but should also be offered live and frozen Daphnia, Artemia, chironomid larvae (bloodworm), etc., on a regular basis.

Not an aggressive fish and can be kept with many cyprinids, loaches, cichlids, catfish and characins, although as always when selecting a compatible community of fish proper research is essential.

It is 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.

Adult females are noticeably deeper-bodied and usually grow slightly larger than males.

Typical egg-scatterer and does not exhibit parental care. Eggs are apparently deposited in batches of around 30 with the fish tending to spawn at dawn or dusk. Incubation is approximately 24 hours.

L. laubuca has several vernacular English names, with others including 'Indian hatchet fish' and 'winged danio'.

Although traditionally considered to occur throughout the Indian subcontinent and most of Southeast Asia, it appears that the species might be restricted to the Ganges-Brahmaputra river system. For example, three new species of Laubuka were described from Sri Lanka in 2008, all of which may have been referred to as L. laubuca in the past. The name L. siamensis has also been revalidated and is currently used to refer to populations from the Mekong watershed in Thailand, Laos, Cambodia, and Vietnam, plus the Chao Phraya basin and other river systems in Thailand and Peninsular Malaysia. The taxonomic status of populations from southern India and Myanmar remains in need of qualification.

Given the distribution of L. siamensis, it seems likely that many of the fish entering the aquarium trade are this species and not L. laubuca. The two species can be distinguished by colour pattern. L. siamensis possesses a black (iridescent blue in live specimens) midlateral stripe on the posterior portion of the body, which terminates in an oval-shaped (vs. roundish in L. laubuca) blotch on the caudal peduncle. There are a series of faint vertical markings in place of the stripe on the anterior portion of the body, and the humeral marking is vertically-oriented and not ocellated (vs. roundish and ocellated in L. laubuca).

In live specimens the posterior stripe in L. siamensis is conspicuously present and not interrupted by any vertical markings (vs. dark stripe less conspicuous, much thinner, and interrupted by irregular vertical markings along the entire body in L. laubuca). Some individuals which we currently include as L. laubuca do not appear to possess a dark stripe at all (see images), however.

L. laubuca can be distinguished from all other members of the genus by the following characters: presence of a dark humeral spot and another on the caudal peduncle, connected by a thin dark stripe which on the anterior portion of the body may only be faintly visible; no dense tuberculation on the lower jaw; body depth 29-32% SL; 17-19 branched anal-fin rays; 31-37 lateral line scales; 6-9 scale rows above lateral line; 15-21 predorsal scales.

The generic name tended to be spelled ‘Laubuca‘ for a number of years, but it is now established that Bleeker used ‘Laubuka‘ first, therefore this spelling has priority.

Among other cyprinids Laubuka species are closely related to the genera Chela, Malayochela, and Devario according to recent phylogentic research, which also supports the splitting of the fomerly much larger Chela grouping into Chela, Malayochela, and Laubuka. There is also a suggestion that L. dadiburjori is not a direct relative of other Laubuka species and may warrant placement in its own genus.