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Syncrossus beauforti (SMITH, 1931)

Chameleon Loach

Classification

Order: Cypriniformes Family: Botiidae

Distribution

Described from ‘Tadi stream’ in Nakhon Si Thammarat province, southern (peninsular) Thailand but subsequently recorded from neighbouring Trang province and much further north in the Ataran River (part of the upper Salween basin and known as ‘Kasat’ river in Thailand), western Thailand/southern Myanmar and the Chao Phraya system, central and western Thailand.

It probably also occurs in the Mae Klong drainage in western Thailand but previous records from the Mekong River apparently refer to two species formerly considered synonyms which Grant (2007) tentatively recognised as valid; S. yunnanensis (Chen, 1980) from the upper Mekong and S. formosanus (Pellegrin & Fang, 1940) from the lower Mekong.

Wild populations appear to have declined by at least 20-29% since 1997 according to a 2007 IUCN survey in which damming of rivers, pollution and collection for the aquarium trade were all cited as contributing factors.

Habitat

Images of the Ataran River habitats depict flowing sections of forest-shaded, seemingly well-oxygenated headwaters with clear water, a mixed sand/rock substrate and lots of submerged driftwood/leaf litter.

In the Hanthayaw (Suriya in Thai) River, upper Ataran basin aquatic plants include Pogostemon helferi and a species of Cryptocoryne while sympatric fish species comprise Acanthocobitis rubidipinnis, Botia kubotai, Syncrossus berdmorei, Pangio fusca, Crossocheilus burmanicus, Parambassis pulcinella, Puntius orphoides, Pethia stoliczkana, Microdevario kubotai, Hampala salweenensis, Poropuntius scapanognathus, Glyptothorax dorsalis, Batasio dayi, B. tigrinus, Akysis vespa, Amblyceps caecutiens, and Tetraodon cutcutia.

In the Ataran other fishes recorded were Schistura vinciguerrae, S. robertsi, Garra sp. ‘redtail’, Mastacembelus armatus plus unidentified members of Devario, Scaphiodonichthys, Tor, Neolissochilus, Garra, and Schistura.

Maximum Standard Length

160 – 180 mm. Records suggesting this species can attain 250 mm are erroneous and apparently refer to S. berdmorei.

Aquarium SizeTop ↑

Minimum base dimensions of 150 ∗ 45 cm or equivalent are required for long-term care.

Maintenance

All botiids need a well-structured set-up although the actual choice of décor is more-or-less down to personal taste. A natural-style arrangement could include a substrate of sand/fine gravel with lots of smooth, water-worn rocks and pebbles plus one or two lumps of driftwood or twisted roots/branches.

Lighting can be relatively subdued and plants able to grow in such conditions like Microsorum, Taxiphyllum barbieri, or Anubias spp. can be added if you wish. These have an added benefit as they can be attached to pieces of décor in such a way as to provide useful shade.

Otherwise be sure to provide plenty of cover as Syncrossus spp. are inquisitive and seems to enjoy exploring their surroundings. Rocks, wood, flower pots and aquarium ornaments can be used in whichever combination to achieve the desired effect.

Bear in mind that these loaches like to squeeze themselves into small gaps and crevices so items with sharp edges should be omitted, and any gaps/holes small enough for a fish to become trapped should be filled in with aquarium-grade silicone sealant. A tightly-fitting cover is also essential as they may also jump at times.

Although botiids don’t require the very turbulent conditions favoured by many balitorids/nemacheilids they do best when the water is well-oxygenated with a degree of flow, are intolerant to accumulation of organic wastes, and requires spotless water in order to thrive. For this reason they should never be introduced to biologically immature set-ups and adapt most easily to stable, mature aquaria. In terms of maintenance weekly water changes of 30-50% tank volume should be considered routine.

Water Conditions

Temperature22 – 30 °C

pH: Seems to prefer slightly acidic to neutral water in the range 6.0 – 7.5.

Hardness36 – 215 ppm

Diet

While Syncrossus spp. appear to be chiefly carnivorous by nature they will also eat vegetative matter if available, sometimes including soft-leaved aquatic plants.

They’re largely unfussy feeders but should be offered a varied diet comprising quality dried products, live/frozen bloodworm, Tubifex, Artemia, etc. plus fresh fruit and vegetables such as cucumber, melon, blanched spinach, or courgette.

Chopped earthworm can also provide a useful source of protein but should be used sparingly, while home-made, gel-based foods using a mixture of natural ingredients are highly recommended. They’ll also prey on aquatic snails but should not be considered the answer to an infestation since if other options are available they will take them. Once settled into an aquarium they’re bold feeders, often rising into midwater.

Behaviour and CompatibilityTop ↑

Can be belligerent and should not be kept with much smaller fishes as they may be intimidated by its size and sometimes very active behaviour. Slow-moving, long-finned species such as ornamental bettas, guppies, and many cichlids should also be avoided as trailing fins can be nipped.

More suitable choices are fast-moving, pelagic cyprinids such as many Devario, Rasbora, ‘Puntius‘, Mystacoleucus, and some Danio spp., while in larger tanks the genera Barilius, Luciosoma, Balantiocheilos, and Barbonymus are options.

In terms of bottom-dwellers it’s often said to do well alongside other robust botiid species though experiences tend to vary with some reporting excessive aggression. Some cobitid/nemacheilid loaches are also possibilities as are members of Epalzeorhynchos, Crossocheilus, and Garra plus many non-territorial catfishes. As always, thorough research prior to selecting a community of fishes is the best way to avoid problems.

These loaches are gregarious, form complex social hierarchies and should be maintained in groups of at least 5 or 6 specimens, preferably 10 or more. When kept singly they can become withdrawn or aggressive towards similarly-shaped fishes, and if only a pair or trio are purchased the dominant individual will typically attack the other(s) repeatedly and may prevent them from feeding.

That said most botiids require regular contact with conspecifics, a fact exemplied by a number of behavioural rituals which have been recorded consistently in aquaria (see ‘Notes’).

Sexual Dimorphism

Adult females should be noticeably stockier than males and probably grow larger, too. Other differences have yet to be documented as far as we know.

Reproduction

Appears not to have been bred in aquaria. Presumably a seasonal, migratory spawner in nature.

NotesTop ↑

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 – LeptobotiaParabotiaSinibotia.
Tribe Botiini – BotiaChromobotiaSyncrossusYasuhikotakia.

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 – LeptobotiaParabotia.
Subfamily Botiinae – BotiaChromobotiaSinibotiaSyncrossusYasuhikotakia.

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.

References

  1. Smith, H. M., 1931 - Proceedings of the United States National Museum 79(2873): 1-48
    Descriptions of new genera and species of Siamese fishes.
  2. Freyhof, J., D. V. Serov and T. N. Nguyen, 2000 - Bonner Zoologische Beiträge 49(1-4): 93-99
    A preliminary checklist of the freshwater fishes of the River Dong Nai, South Vietnam.
  3. Grant, S., 2007 - Ichthyofile Number 2: 1-106
    Mainland fishes of the genus Syncrossus Blyth, 1860 (Teleostei: Botiidae).
  4. Kottelat, M., 2001 - WHT Publications, Colombo: 1-198
    Fishes of Laos.
  5. 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).
  6. Kottelat, M. 2004 - Zootaxa 401: 1-18
    Botia kubotai, a new species of loach (Teleostei: Cobitidae) from the Ataran River basin (Myanmar), with comments on botiine nomenclature and diagnosis of a new genus.
  7. Kottelat, M. and X. Chu, 1987 - Zoological Research 8(4): 393-400
    The botiine loaches (Osteichthyes: Cobitidae) of the Lancangjiang (Upper Mekong) with description of a new species.
  8. Nalbant, T. T., 2004 - Travaux du Museum d'Histoire Naturelle : 269-277
    Hymenphysa, Hymenophysa, Syncrossus, Chromobotia and other problems in the systematics of Botiidae. A reply to Maurice Kottelat.
  9. Nalbant, T. T., 2002 - Travaux du Museum d'Histoire Naturelle : 309-333
    Sixty million years of evolution. Part one: family Botiidae (Pisces: Ostariophysi: Cobitoidea).
  10. Rainboth, W. J., 1996 - FAO, Rome: 1-265
    Fishes of the Cambodian Mekong. FAO Species Identification Field Guide for Fishery Purposes.
  11. Tang, Q., B. Xiong, X. Yang, and H. Liu, 2005 - Hydrobiologia 544(1): 249-258
    Phylogeny of the East Asian botiine loaches (Cypriniformes, Botiidae) inferred from mitochondrial cytochrome b gene sequences.
  12. Šlechtová, V., J. Bohlen, J. Freyhof, and P. Ráb, 2006 - Molecular Phylogenetics and Evolution 39(2): 529-541
    Molecular phylogeny of the Southeast Asian freshwater fish family Botiidae (Teleostei: Cobitoidea) and the origin of polyploidy in their evolution.

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