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Homaloptera confuzona KOTTELAT, 2000

Etymology

A contraction of the Latin confusus, meaning confused, and zona, meaning belt.

Classification

Order: Cypriniformes Family: Balitoridae

Distribution

Most records pertain to the Mekong River basin downstream of the Khone waterfalls in Laos and Cambodia, but this species is also known from some smaller river drainages in southern Thailand, including parts of the Mae Klong system.

Type locality is ‘Khlong Fit at Ban Kraduk Chang, road 3157 from Trat to borai, about 2-3 kilometers after junction with road 3271, 12°28′N, 102°38′E, Trat Province, Thailand’.

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 show 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.

We’ve been unable to obtain details of sympatrically-occurring species but other fishes from the Mekong basin inhabiting similar environments include Acanthocobitis zonalternans, Annamia normani, Nemacheilus binotatus, N. pallidus, N. platiceps, Sewellia breviventralis, S. lineolata, S. speciosa, Lepidocephalichthys berdmorei, L. furcatus, L. hasselti, Crossocheilus atrilimes, C. reticulatus, plus various Barilius, Devario, ‘Puntius‘, Rasbora, Acanthopsoides, Balitora, Hemimyzon, Schistura, Akysis, Glyptothorax, Rhinogobius and other Homaloptera species.

Maximum Standard Length

75 – 85 mm.

Aquarium SizeTop ↑

An aquarium with base dimensions of 120 ∗ 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 gravelsand 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 although rarely a feature of the natural habitat aquatic plants from adaptable genera such as MicrosorumCrinum and Anubias spp. can also be added. The latter are particularly useful as Homaloptera spp. appear to enjoy resting on their leaves.

Since it needs stable water conditions and feeds on biofilm this species should never be added to a biologically immature set-up, and a tightly-fitting cover is necessary since it can literally climb glass. While regular partial water changes are essential aufwuchs can be allowed to grow on all surfaces except perhaps the viewing pane.

Water Conditions

Temperature20 – 25.5 °C

pH6.0 – 7.5

Hardness18 – 268 ppm

Diet

Homaloptera spp. are specialised grazers feeding on biofilm, small crustaceans, insect larvae and other invertebrates.

In captivity some sinking dried foods may be accepted but regular meals of live or frozen DaphniaArtemiabloodworm, 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.

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 BariliusDischerodontusGarraDevario, some Rasbora, gobies of the genera RhinogobiusSicyopterus and Stiphodon plus GlyptothoraxAkysis 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 singly or in smaller groups it’s less bold.

The interaction between individuals is also interesting to watch and a group will typically arrange themselves close to one another facing directly into the water flow at certain times of day.

Sexual Dimorphism

Sexually mature females are usually a little larger and fuller-bodied than males.

Reproduction

Presumably a seasonal spawner in nature but nothing has been recorded in aquaria.

NotesTop ↑

This species is available in the aquarium trade from time-to-time though it’s not always identified correctly.

It can be told apart from congeners by the following unique combination of characters: body colour yellowish to reddish brown, with 4 irregularly-shaped or incomplete dark bars on body (sometimes absent); anterior body bar at level of pectoral-fin, narrow, usually reaching pectoral-fin; second bar at dorsal-fin origin, very broad dorsally, extending along base of whole fin, more or less triangular in shape, restricted to upper half of body or continuing to pelvic-fin origin via a thin extension; third bar above anal-fin base, very irregular, often restricted to upper half of body or missing entirely; fourth bar at base of caudal peduncle and continuous with a dark blotch on caudal-fin base and lower caudal-fin lobe; second and third bars often connected along the dorsal surface, first and second rarely so; presence of a conspicuous stripe from tip of snout through eye to nape and another extending from eye towards throat; colour pattern on fins less variable, 6-7 simple and 10-11 bracnhed pectoral-fin rays; 2 simple and 7 branched pelvic-fin rays; 62-67 + 2 lateral line scales.

It’s a member of the H. ocellata ’group’ within the genus which currently contains H. ocellataH. bilineataH. confuzonaH. orthogoniataH. ogilviei and H. parclitella.

Following Tan and Ng (2005) these share possession of a colour pattern with reddish tints and dark brown head markings, elongate head, slightly compressed body, 61-77 lateral line scales and dorsal-fin origin placed in advance of pelvic-fin origin.

H. confuzonaH. orthogoniata and H. parclitella appear very similar at first glance but can be told apart by a few characters, the most useful of which to aquarists are the dark markings extending from the snout over the dorsal surface. These form a series of variable saddle-shaped blotches in all three species but there are some marked differences.

For example in H. orthogoniata and H. parclitella the ‘saddles’ are noticeably broader, more regularly-shaped and well-defined than in H. confuzona and usually extend into the lower half of the body.

Further, H. parclitella always has two saddles and H. orthogoniata three, whereas in H. confuzona there may be up to four irregularly shaped markings which are often restricted to the upper half of the body. One shared feature is an additional dark bar at the caudal peduncle.

Another feature shared by members of the H. ocellata group is keeled scales; for example in H. bilineata each scale has a single, wide keel orientated posteriorly. In H. confuzona the keels are rounded and in H. ogilviei elongate; in both cases they’re positioned at the posterior edge of the scale.

In H. orthogoniataH. ocellata and H. parclitella a central, broad keel is flanked by two smaller ones. Other defining characters for H. parclitella include 5 branched anal-fin rays, 2 simple and 8-9 branched pelvic-fin rays, 5 simple and 12-13 branched pectoral-fin rays and 12-14 scale rows above the pelvic-fin origin.

The reason for grouping certain species together is to facilitate easier reference because Homaloptera has long been considered a polyphyletic assemblage (Kottelat, 1998), and some former members have already been moved into the revalidated genus Homalopteroides (Fowler, 1905) by Randall and Page (2012) on the basis of their oral morphology.

Homalopteroides currently contains  H. wassinkiiH. modestusH. nebulosusH. rupicolaH. smithiH. tweediei, H. stephensoni, H. indochinensisH. weberi, H. yuwonoi and possibly H. manipurensis.

Following Randall and Page the species remaining in Homaloptera are distributed between three subgenera of which the H. ocellata group retains the name Homaloptera since H. ocellata is the type species of the genus.

A group containing H. leonardiH. ophiolepisH. sexmaculataH. yunnanensis and H. zollingeriamong others, is contained within the subgenus Balitoropsis Smith, 1945.

The Sumatran species H. gymnogasterH. heterolepisH. ripleyi and H. vanderbilti constitute the subgenus Homalopterula Fowler, 1940, while those from southern India may represent a distinct genus as well.

Kottelat (2012) considers these subgenera as valid, distinct genera, whereas Randall and Page (2012) concluded that further study is necessary in order to be certain of their taxonomic status. We follow the latter for the time being.

All Homaloptera spp. make fascinating aquarium inhabitants and are often referred to as ‘lizard’ 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. Kottelat, M., 2000 - Journal of South Asian Natural History 5(1): 37-82
    Diagnoses of a new genus and 64 new species of fishes from Laos (Teleostei: Cyprinidae, Balitoridae, Bagridae, Syngnathidae, Chaudhuriidae and Tetraodontidae).
  2. Alfred, E. R., 1967 - Copeia 1967(3): 587-591
    Homaloptera ogilviei, a new species of homalopterid fish from Malaya.
  3. Beamish, F. W. H., P. Sa-ardrit and V. Cheevaporn, 2008 - Journal of Fish Biology 72(10): 2467–2484
    Habitat and abundance of Balitoridae in small rivers of central Thailand.
  4. Blyth, E., 1860 - Journal and Proceedings of the Asiatic Society of Bengal 29(2): 138-174
    Report on some fishes received chiefly from the Sitang River and its tributary streams, Tenasserim Provinces.
  5. Kottelat, M., 1998 - Ichthyological Exploration of Freshwaters 9(3): 267-272
    Homaloptera yuwonoi, a new species of hillstream loach from Borneo, with a new generic name for H. thamicola (Teleostei: Balitoridae).
  6. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
    Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
  7. 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).
  8. Roberts, T. R., 1993 - Zoologische Verhandelingen (Leiden) 285(1): 1-94
    The freshwater fishes of Java, as observed by Kuhl and van Hasselt in 1820-23.
  9. Roberts, T. R., 1989 - Memoirs of the California Academy of Sciences 14: 1-210
    The freshwater fishes of Western Borneo (Kalimantan Barat, Indonesia).
  10. Tan, H. H. and M. Kottelat, 2009 - Ichthyological Exploration of Freshwaters 20(1): 13-69
    The fishes of the Batang Hari drainage, Sumatra, with description of six new species.
  11. Tan, H. H. and P. K. L. Ng, 2005 - Ichthyological Exploration of Freshwaters 16(1): 1-12
    Homaloptera parclitella, a new species of torrent loach from the Malay Peninsula, with redescription of H. orthogoniata (Teleostei: Balitoridae).
  12. 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).
  13. 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.

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