Homalopteroides weberi (HORA, 1932)

SynonymsTop ↑

Homaloptera weberi Hora 1932

Etymology

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

weberi:  in honor of ichthyologist Max Weber (1852-1937)

Classification

Order: Cypriniformes Family: Balitoridae

Distribution

Type locality is ‘Akar River, Sarawak state, Borneo, East Malaysia’, and this species may be endemic to the Malaysian state of Sarawak in western Borneo.

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.

Maximum Standard Length

45 – 50 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: 20 – 25 °C

pH: 6.0 – 7.5

Hardness: 36 – 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

Unrecorded, but in congeners sexually mature females are usually a little larger and fuller-bodied than males.

Reproduction

Unrecorded

NotesTop ↑

This species is poorly known in the aquarium hobby and may not yet have been traded.

Kottelat (2012) questioned that this species might be synonymous with Balitoropsis stephensoni (Hora 1921) but Randall and Page (2012, 2014, 2015) consider it distinct and in Homalopteroides.

Following Randall and Page (2012) it possesses: 2 dark bands on the caudal-fin; 16 total pectoral-fin rays; pectoral-fin length greater than head length;  scale count above and below line to pelvic-fin 6-7½/7-8½; 46-48 pored lateral-line scales; presence of an axillary lobe; pelvic-fin extending to or past anus; orbital length equal to interopercular width.

The genus Homalopteroides was itself revalidated by Randall and Page (2012) and 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 is widely-distributed across most of Eurasia with the Indian subcontinent, Southeast Asia and China representing particular centres of species diversity.

It was first proposed as a genetically distinct grouping in 2006, and according to current knowledge contains over 32 genera of which the most well-known in the aquarium hobby include Annamia, Beaufortia, Gastromyzon, Homaloptera, Liniparhomaloptera, Pseudogastromyzon, Sewellia, Sinogastromyzon and Vanmanenia.

These were previously considered members of the family Balitoridae, subfamily Balitorinae, but phylogenetic studies have revealed that though closely related Balitorid and Nemacheilid loaches did not evolve from the same common ancestor and represent separate genetic lineages.

References

1. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
2. 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).
3. Randall, Z.S. and L.M. Page, 2015 - Zootaxa 3926, Vol 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
4. 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).
5. 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.