Sinogastromyzon tonkinensis PELLEGRIN & CHEVEY, 1935

Etymology

Sinogastromyzon: from the Latin sina, meaning ‘from China’ (used as a prefix in this case), Greek gaster, meaning stomach, and Greek myzo, meaning ‘to suckle’.

tonkinensis: named for Tonkin, Vietnam, type locality of this species.

Classification

Order: Cypriniformes Family: Balitoridae

Distribution

Type locality is ‘Lai Chau, Tonkin, northern Vietnam’, in the lower Red River system, and this species appears endemic to that drainage in Yunnan province, southern China and northern Vietnam.

Habitat

An obligate dweller of swiftly-flowing streams and headwaters containing clear, oxygen-saturated water. It often inhabits riffles and runs and is likely to display a preference for shallower zones.

Substrates are generally composed of gravel, rocks, boulders or bedrock carpeted with a rich biofilm formed by algae and other micro-organisms.

Patches of aquatic plants are only occasionally present but riparian vegetation is usually well-developed.

In 2009 at a locality in the Menyejiang River, a tributary of the Lixianjiang River within the Red River basin, Puer County, Yunnan province, China, it was collected alongside the congener Sinogastromyzon macrostoma plus Vanmanenia sp., Beaufortia sp., Garra sp. and Pseudecheneis paviei.

On 06.01.2009 water parameters were temperature 17 ºC/62.6°F, pH 8.8, conductivity 170 µS/cm, TDS 85 mg/l, GH 2º GH, KH 3º.

At the type locality of the congener S. lixianjiangensis sympatric species included Balitora kwangsiensis, Glyptothorax quadriocellatus, Garra orientalis, Hemibagrus pluriradtus, Poropuntius huangchieni, Pseudecheneis paviei, Scaphiodonichthys acanthopterus, Schistura callichromus, Schistura laterivittata, Sinogastromyzon macrostoma, S. multiocellum, S. lixianjiangensis and Vanmanenia tetraloba.

Maximum Standard Length

55 – 65 mm.

Aquarium SizeTop ↑

Minimum base dimensions of 75 ∗ 30 cm or equivalent are recommended.

Maintenance

Most importantly the water must be clean and well-oxygenated so we suggest the use of an over-sized filter as a minimum requirement.

Turnover should ideally be in excess of 15-20 times per hour so additional powerheads or airstones should be employed as necessary. Truly torrential conditions are unnecessary but tolerated.

Base substrate can either be of gravel, sand or a mixture of both to which should be added a layer of water-worn rocks and pebbles of varying sizes and perhaps some driftwood roots and branches.

Although not a feature of the natural habitat aquatic plants can be used with hardier genera such as Microsorum, Crinum and Anubias spp. likely to fare best.

Like many species 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.

As stable water conditions are obligatory for its well-being this fish should never be added to biologically-immature aquaria, and be sure to use a tightly-fitting cover as it can climb glass.

Water Conditions

Temperature: For general care 15 – 22 °C is recommended but it can withstand temporarily warmer conditions provided dissolved oxygen levels are maintained.

pH: 7.0 – 9.0

Hardness: 36 – 215 ppm

Diet

Sinogastromyzon spp. are specialised micropredators and biofilm grazers feeding on small crustaceans, insect larvae and other invertebrates with some algae taken as well.

In captivity some sinking dried foods may be accepted but daily meals of live or frozen Daphnia, Artemia, bloodworm, etc., are essential for the maintenance of good health and it’s highly preferable if the tank contains rock and other solid surfaces with growths of algae and other aufwuchs.

If unable to grow sufficient algae in the main tank or you have a community containing numerous herbivorous fishes which consume what’s available quickly it may be necessary to maintain a separate tank in which to grow algae on rocks and switch them with those in the main tank on a cyclical basis.

Such a ‘nursery‘ doesn’t have to be very large, requires only strong lighting and in warmer climates can be kept outdoors.

Balitorids are often seen on sale in an emaciated state which can be difficult to correct.

A good dealer will have done something about this prior to sale but if you decide to take a chance with severely weakened specimens they’ll initially require a constant source of suitable foods in the absence of competitors if they’re to recover.

Behaviour and CompatibilityTop ↑

Very peaceful although its environmental requirements limit the selection of suitable tankmates somewhat, plus it should not be housed with any much larger, more aggressive, territorial or otherwise competitive fishes.

Potential options include small, pelagic cyprinids such as Tanichthys, Danio, and Rasbora, stream-dwelling gobies from the genera Rhinogobius, Sicyopterus, and Stiphodon, plus rheophilic catfishes like Glyptothorax, Akysis and Hara spp.

Some loaches from the families Nemacheilidae, Balitoridae and Gastromyzontidae are also suitable but others are not so be sure to research your choices thoroughly before purchase.

Regarding conspecifics it’s best described as loosely gregarious so buy a group of 4 or more if you want to see its most interesting behaviour.

It’s territorial to an extent with some individuals appearing more protective of their space than others (often a prime feeding spot). This may be related to gender since males in some related species are known to be more aggressive than females.

At any rate physical damage is rare and such battles are very entertaining to watch. Sinogastromyzon spp. tend to be quite reclusive compared to most other balitorids and maintaining them in numbers may also help offset this to a certain extent.

Sexual Dimorphism

Males have a relatively slimmer body shape, and the angle at which the pectoral-fin meets the head is comparatively sharp, whereas the opposite is true in femaes (see images).

These differences are most obvious when the fish is viewed from above or below.

Reproduction

Unrecorded.

NotesTop ↑

This species is poorly-known in the aquarium hobby but does appear to have been exported on a handful of occasions.

We’ve been unable to obtain a full diagnosis so far but following the key in Liu et al. it can be told apart from congeners via the following combination of characters: no scales on the dorsum of paired fins or the region between axilla of pectoral-fin and pelvic-fin origin; tip of pelvic-fin extends beyond anus; presence of regular blotches on the dorsum of the body; caudal-peduncle length greater than its depth; 48–68 lateral-line scales; body depth fits less than 5 times in body length; anal fin with 1 weak spine.

It occurs syntopically with S. multiocellum, S. lixianjiangensis and S. macrostoma with these four most-easily separated by examining the mouthparts. S. tonkinensis possesses 2 pairs of long, relatively thin barbels at each corner of the mouth and the mouth measures 39.8-48.3 % of head width (hw).

S. multiocellum has 2 pairs of long, relatively thick barbels and the mouth measures 25.0-33.2 % hw, S. lixianjiangensis has 2 pairs of minute barbels and the mouth measures 34.6-40.1 % hw, and S. macrostoma also has minute barbels but the mouth measures 54.2–73.0 % hw.

Sinogastromyzon is distinguished from other balitorid genera by a combination of characters as follows: head and anterior portion of body relatively short, depressed and ventrally flattened; paired fins horizontal and laterally expanded, with 2 or more simple rays; pelvic fins fused posteriorly to form a sucking disk; eyes superolateral; mouth inferior and transverse; 4 rostral and 4 maxillary barbels aligned in rows; gill opening relatively large and extending to pectoral-fin.

The genus currently appears restricted to southern mainland China, Taiwan, Laos, and northern Vietnam.

Sinogastromyzon spp. have specialised morphology adapted to life in fast-flowing water. The paired fins are orientated horizontally, head and body flattened, and pelvic fins fused together.

These features form a powerful sucking cup which allows the fish to cling tightly to solid surfaces. The ability to swim in open water is greatly reduced and they instead ‘crawl’ their way over and under rocks.

The family Balitoridae as recognised by Kottelat (2012) is widely-distributed across much of the Indian subcontinent, Southeast Asia and China.

Kottelat (2012) also considers the family Gastromyzontidae valid and many former balitorids are now contained within that group, but Sinogastromyzon is retained in Balitoridae.

References

1. Endruweit, M. (ed), 2013 - World Wide Web electronic publication, www.aquariophil.org: Accessed on 13.01.09
   Aquariophil.
2. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
3. Kottelat, M., 2001 - Environment and Social Development Unit, East Asia and Pacific Region. The World Bank.: i-iii + 1-123 + 1-18
   Freshwater fishes of northern Vietnam. A preliminary check-list of the fishes known or expected to occur in northern Vietnam with comments on systematics and nomenclature.
4. Kottelat, M., 2013 - Raffles Bulletin of Zoology Supplement 27: 1-663
   The fishes of the inland waters of southeast Asia: a catalogue and core bibliography of the fishes known to occur in freshwaters, mangroves and estuaries.
5. Kottelat, M. and X. L. Chu, 1988 - Revue Suisse de Zoologie 95(1): 181-201
   A synopsis of Chinese balitorine loaches (Osteichthyes: Homalopteridae) with comments on their phylogeny and description of a new genus.
6. Liu, S-W., X-Y. Chen, and J-X. Yang, 2010 - Environmental Biology of Fishes 87(1): 25-37
   Two new species and a new record of the genus Sinogastromyzon (Teleostei: Balitoridae) from Yunnan, China.
7. Liu, S.-W., X.-Y. Chen and J.-X. Yang, 2010 - Environmental Biology of Fishes
   Two new species and a new record of the genus Sinogastromyzon (Teleostei: Balitoridae) from Yunnan, China.
8. Tang, W.-Q. and Y.-Y. Chen, 2000 - Journal of Shanghai Fisheries University 9(1): 1-9
   Study on taxonomy of Homalopteridae.