Homalopteroides modestus (VINCIGUERRA, 1890)

SynonymsTop ↑

Helgia modesta Vinciguerra, 1890; Homaloptera modesta (Vinciguerra, 1890)

Etymology

Homalopteroides:  From the ancient Greek εἶδος, ‎eîdos (= form, likeness, resemblance) and the generic Homaloptera.

modestus:  Latin for modest; possibly a reference to the less striking colouration of this species.

Classification

Order: Cypriniformes Family: Balitoridae

Distribution

The type series was collected from Meekalan and Meetan in what was formerly known as Tenasserim Division, southern Myanmar, this corresponding to the modern-day states of Mon and southern Kayin¡ in Tanintharyi Region.

H. modestus is known to occur in the Salween, Mae Klong, and Tenasserim river systems in southern Myanmar and western Thailand, of which the latter two drain the Tenasserim Range of mountains.

Earlier records from Borneo and India are now accepted to be incorrect and reprsent different, albeit related, species.

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.

Other loach species inhabiting such environments, and which share a similar range with H. modestus include Acanthocobitis pictilis and Schistura mahnerti.

Maximum Standard Length

The largest officially-recorded individual measured 44 mm.

Aquarium SizeTop ↑

An aquarium with base dimensions of 60 ∗ 30 cm or equivalent is required for long-term maintenance.

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 10-15 times per hour so additional powerheads, airstones, etc., should be employed as necessary to achieve the desired flow and oxygenation.

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.

Driftwood roots and branches are also suitable and aquatic plants from adaptable genera such as Microsorum, Crinum and Anubias spp. can also be included. The latter are particularly useful as Homalopteroides spp. appear to enjoy resting on their leaves.

Since it requires stable water conditions this species should never be added to a biologically immature set-up.

Water Conditions

Temperature: 18 – 25.5 °C

pH: 6.0 – 7.5

Hardness: 18 – 215 ppm

Diet

Homalopteroides spp. are specialised micropredators feeding on small crustaceans, insect larvae and other invertebrates.

In captivity some sinking dried foods may be accepted but regular meals of live or frozen Daphnia, Artemia, bloodworm, etc., are essential for the maintenance of good health.

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 continual, easily-obtainable source of suitable foods in the absence of competitors if they’re to recover.

Behaviour and CompatibilityTop ↑

Not an aggressive fish although its particular requirements limit the choice of suitable tankmates.

Species inhabiting similar environments include Barilius, Discherodontus, Garra, Devario, some Rasbora, gobies of the genera Rhinogobius, Sicyopterus and Stiphodon plus Glyptothorax, Akysis and Oreoglanis spp. catfishes.

Many loaches from the family Nemacheilidae and most from Balitoridae are also suitable although harmless squabbles may occur with the latter group in particular. Research your choices before purchase to be sure.

It’s found living in aggregations in nature so buy six or more to see it at its best as when kept in smaller group it may be less bold. The interaction between individuals is also interesting to watch.

Sexual Dimorphism

Sexually mature females should be a little larger and fuller-bodied than males.

Reproduction

Unrecorded.

NotesTop ↑

This species was redescribed by Randall and Page (2012) based on specimens collected from the Mae Klong river system in western Thailand that had previously been identified as the congener H. smithi.

It can be told apart from related species by the following combination of characters: caudal-fin colour pattern consisting of a black proximal bar, a black distal bar and a black median blotch; 15 total pectoral-fin rays; pectoral-fin length greater than head length;  scale count above and below line to pelvic-fin 5-6½/5-5½; 39-44 pored lateral-line scales; absence of an axillary lobe; pelvic-fin not extending to or past anus; orbital length less than interopercular width in adults; maxillary barbel reaching or slightly passing the anterior rim of the orbital.

The genus Homalopteroides Fowler 1905 was revalidated by Randall and Page (2012) on the basis of its unique mouth morphology.  It is told apart from the related Homaloptera by the following character combination: dorsal-fin origin above pelvic-fin; ≤ 60 lateral-line scales; ≤ 30 predorsal scales; oral morphology consisting of two thin and widely separated rostral barbels on each side of the mouth, thin crescent-shaped lips, the absence of any structure such as a mental pad or lobes between the lateral portions of the lower lip, and a chin that extends anterior to the lateral portions of the lower lip.

Homalopteroides currently (February 2016) contains  H. wassinkii, H. modestus, H. nebulosus, H. rupicola, H. smithi, H. tweediei, H. stephensoni, H. indochinensis, H. weberi, H. yuwonoi, H. avii and possibly H. manipurensis. These are all former members of Homaloptera, a polyphyletic grouping which following Randall and Page (2015) was split into the genera Homaloptera, Homalopterula, Pseudohomaloptera, Homalopteroides, Balitoropsis, and Ghatsa.

Homalopteroides spp.  are sometimes referred to as ‘lizard’ or ‘gecko’ loaches due to their behaviour and appearance. Like all balitorids they have morphology specialised for life in fast-flowing water, i.e., the paired fins are orientated and extended horizontally, head and body flattened, belly depressed.

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 appear to crawl and hop their way over rocks and other surfaces.

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

References

1. Vinciguerra, D., 1890 - Annali del Museo Civico di Storia Naturale di Genova (Serie 2) v. 9: 129-362
   Viaggio di Leonardo Fea in Birmania e regioni vicine. XXIV. Pesci.
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., 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.
4. Randall, Z. S. and L. M. Page, 2012 - Zootaxa 3586: 329-346
   Resurrection of the genus Homalopteroides (Teleostei: Balitoridae) with a redescription of H. modestus (Vinciguerra 1890).
5. Randall, Z. S. and L. M. Page, 2015 - Zootaxa 3926(1): 57-86
   On the paraphyly of Homaloptera (Teleostei: Balitoridae) and description of a new genus of hillstream loaches from the Western Ghats of India.
6. Tang, Q., H. Liu, R. Mayden and B. Xiong, 2006 - Molecular Phylogenetics and Evolution 39(2): 347-357
   Comparison of evolutionary rates in the mitochondrial DNA cytochrome b gene and control region and their implications for phylogeny of the Cobitoidea (Teleostei: Cypriniformes).
7. Šlechtová, V., J. Bohlen and H. H. Tan, 2007 - Molecular Phylogenetics and Evolution 44(3): 1358-1365
   Families of Cobitoidea (Teleostei; Cypriniformes) as revealed from nuclear genetic data and the position of the mysterious genera Barbucca, Psilorhynchus, Serpenticobitis and Vaillantella.