Incisilabeo behri

Incisilabeo: from the Latin incisus, meaning 'cut up, hewn open', and the generic name Labeo, to which this genus is related.

behri: in honour of "the late Otto Behr, of Lopez, Pennsylvania (USA), to whom the Academy of Natural Sciences of Philadelphia was indebted for many specimens of the natural history of Thailand".

Native to the Mekong river system in southern China, Laos, Thailand, Vietnam, and Cambodia, and possibly the Chao Phraya watershed in central Thailand although this appears to be in question.

Type locality is 'Mekong River at Kemrat [Kemarat], Thailand'.

Inhabits main river channels and large, deep tributaries with rocky substrates, and forms schools with other large, benthic fish species, including Cirrhinus microlepis, Labeo chrysophekadion, Cyclocheilichthys enoplos, and Yasuhikotakia modesta.

It undergoes seasonal migrations, moving upstream into the Sekong, Sesan, and Srepok rivers in May and June, at the onset of the wet season, and returning downstream during the dry months between November and February. There may be two separate migration events; one involving young fish moving to favourable foraging grounds, and the other with sexually mature individuals travelling in order to spawn.

Suitable only for public installations or the very largest, highly-specialised private aquaria.

A large, mature filter system, rigorous maintenance regime comprising weekly water changes of 50-70% tank volume, and provision of highly-oxygenated water with a degree of movement should be considered mandatory.

A specialised grazer of algae and associated organisms which it rasps from the surface of rocks and other solid objects using its specialised mouthparts.

May be aggressive in confined spaces, i.e., smaller aquaria.

Although this species is patently unsuitable for the home aquarium juveniles are available on a relatively regular basis, albeit never in large numbers.

This monotypic genus is separated from the closely-related taxon Bangana by presence of a unique and conspicuous transverse notch across the top of the head, comparable in position to the ethmoid furrow in Bangana species. This notch approaches the eye, and the top of the head bulges forward, with the nostrils located partially beneath this projection and immediately anterior to the eyes. Tubercles cover the upper portion of the rostral fold, lower part of the notch, and upper surface of the forehead projection, and the body and head are conspicuously deep. Colour pattern is also unique when compared to all known Bangana species, with the head yellowish to orangish-brown and body grey to greyish-brown.

When describing I. behri, Fowler erected the subgenus Incisilabeo for it, but this fell out of use and the species was placed in Tylognathus for a few years, until this was revealed to be a synonym of Bangana by Kottelat (1984). It then remained in Bangana until 2011 when Kottelat and Steiner used the characters described above to revalidate Incisilabeo.

This species is usually included in the subfamily Labeoninae/Cyprininae or tribe Labeonini (name varies with author) which by recent thinking is further divided into four subtribes; Labeoina, Garraina, Osteochilina, and Semilabeoina (Yang et al., 2012)[7]. Among these, Incisilabeo is included in the Labeoina alongside Bangana sensu stricto (which includes the genus Nukta), Cirrhinus sensu stricto, Cirrhinus microlepis (which is of a different genetic lineage to other Cirrhinus species), Gymnostomus, and Labeo sensu stricto (which includes Gibelion).