This species is very similar in appearance to S. berdmorei which is native to India and Myanmar, and has been widely mislabelled under that name in older aquarium literature.
The two can appear identical on first glance but there are some notable differences, most obviously possession of 9-10 branched dorsal-fin rays in S. beauforti vs. 11-14 in S. bermorei, and the fact that even young specimens of S. beauforti exhibit laterally-orientated rows of small, dark markings running across the entire body and head whereas in S. berdmorei these markings are relatively larger and in young individuals appear first in the region behind the opercle, extending further along the body as they mature.
In adult specimens of both species the vertical body bars sometimes fade leaving only the rows of dark markings, particularly in S. beauforti.
Syncrossus is told apart from other botiid genera by possession of a unique, sickle-shaped anterior process on the premaxilla which surrounds a cavity between the left and right processes, plus the rostral process is short with no ridge along the inner edge.
Members can be further distinguished via the following combination of characters: the mental lobe is not developed into a barbel and has a pair of fleshy papillae at the anterior edge; the fronto-parietal fontanelle is large and wide; the anterior chamber of the gas bladder is partially covered by a bony capsule and the posterior chamber is large; the top of the supraethmoid is narrow; the optic foramen is large; the suborbital spine is not strongly curved backwards, and has a bifid structure; the head is naked (based on Taki, 1972: 74, 76); the colour pattern consists of regular, narrow bars while some species possess additional, longitudinal rows of black spots.
The family Botiidae was first proposed as a genetically distinct grouping by Nalbant (2002) having previously been considered a subfamily (Botiinae) of the family Cobitidae. Nalbant also moved some previous members of Botia into the new genus Yasuhikotakia based on a number of morphological characters.
Later Kottelat (2004) made further modifications to the taxonomy, raising the new genus Chromobotia for B. macracanthus and confirming that species previously included in the genus Hymenophysa should instead be referred to Syncrossus.
The former alteration was based on colour pattern plus some morphological characters and the latter because Hymenophysa not only represents a spelling mistake (McClelland's original spelling was Hymenphysa) but is a junior synonym of Botia. As a result of these works the family Botiidae thus includes seven genera divided into two tribes within which Botia appears to be the most basal lineage:
Tribe Leptobotiini - Leptobotia, Parabotia, Sinibotia.
Tribe Botiini - Botia, Chromobotia, Syncrossus, Yasuhikotakia.
Phylogenetic studies by Tang et al. (2005) and Šlechtová et al. (2006) have largely confirmed this system to be correct although the latter disagreed with the placement of Sinibotia, finding it to be more closely related to the tribe Botiini.
Interestingly, Yasuhikotakia nigrolineata and Y. sidthimunki were found to be more closely-related to both Sinibotia and Syncrossus than other species of Yasuhikotakia, though no nomenclatural changes were actioned with the need for more detailed study given as reasoning. Šlechtová et al. also proposed the use of subfamily names under the following system:
Subfamily Leptobotiinae - Leptobotia, Parabotia.
Subfamily Botiinae - Botia, Chromobotia, Sinibotia, Syncrossus, Yasuhikotakia.
Within these Botia appears to be the basal, i.e., most ancient lineage and in a more-detailed phylogenetic analysis Šlechtová et al. (2007) confirmed the validity of the family Botiidae with all genera listed above as members rather then being grouped into subfamilies. This latter, simplified, system is the one we currently follow here on SF.
Some behavioural routines exhibited by Syncrossus spp. have been recorded often enough that they've been assigned non-scientific terms for ease of reference. For example during dominance battles (these occur most frequently when the fish have been introduced to a new tank, or new individuals added to an existing group) the protagonists normally lose much of their body patterning and colouration, a phenomenon that's come to be known as 'greying out'. Such displays will sometimes also happen within an established group as individuals seek to improve social ranking but are usually nothing to worry about.
Interestingly some observations suggest that the character of the highest-ranked, or alpha, fish appears to affect that of the whole group though it must be said that scientific studies of botiid loach behaviour are virtually non-existent. It certainly seems that they display a degree of 'personality' with some specimens being naturally bolder/more aggressive than others. The alpha is normally the largest specimen within the group and often female.
Sound also appears to be an important factor in communication since these loaches are able to produce audible clicking sounds, these increasing in volume when the fish are excited. The behavioural aspects of this phenomenon remain largely unstudied but the sounds are thought to be produced by grinding of the pharyngeal teeth.
All Syncrossus spp. possess sharp, motile, sub-ocular spines which are normally concealed within a pouch of skin but erected when an individual is stressed, e.g., if removed from the water. Care is therefore necessary as these can become entangled in aquarium nets and with larger specimens in particular break human skin.
Botiids are also susceptible to a condition commonly referred to as 'skinny disease' and characterised by a loss of weight. This is especially common in newly-imported specimens and is thought to be caused by a species of the flagellate genus Spironucleus. It is treatable although the recommended medication varies depending on country. Hobbyists in the UK tend to use the antibiotic Levamisole and those in the United States Fenbendazole (aka Panacur), for example.
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