Homalopteroides stephensoni

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

stephensoni: Honours Lieutenant Colonel John Stephenson (1871-1933), biology professor at Government College, Lahore (Pakistan), who taught Hora.

Described from the 'upper Mahakam river, East Kalimantan province, Borneo' and also known from West Kalimantan (collected from the Danau Sentarum National Park and Pinoh river), Central Kalimantan (Katingan and Barito river systems), East Kalimantan (Malinau river basin) in the Indonesian part of the island, as well as parts of Sabah (near the town of Tinom; Danum Valley) and Sarawak (Rejang and Tatau river systems) provinces in the Malaysian portion.

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.

Juveniles are often found in slower-moving stretches with gravel substrate and submerged tree roots. In both cases patches of aquatic plants are only occasionally present but riparian vegetation is usually well-developed.

At the type locality of Homaloptera batek (Tan, 2009)[5] H. stephensoni was collected from a foothill stream running swiftly over a rocky/gravel substrate with clear water of pH 6.4.

It was observed only in the fastest-flowing riffles and other fish species included Garra borneensis, Paracrossocheilus vittata, Rasbora elegans, Homaloptera orthogoniata, Nemacheilus spiniferus plus unidentified species of Hypergastromyzon, Gastromyzon and Glyptothorax.

An aquarium with base dimensions of 60 ∗ 30 cm24 ∗ 12 in or equivalent is required for long-term 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 to achieve the desired flow and oxygenation if necessary.

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 although rarely a feature of the natural habitat aquatic plants from 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.

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.

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 singly, in pairs or trios it's less bold. The interaction between individuals is also interesting to watch.

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

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

This species is poorly-known in the aquarium hobby and may never have been exported for the ornamental trade.

It can be told apart from congeners by the following combination of characters as per the redescription by Tan (2009): sub-inferior mouth with thin barbels; five principle, 12-13 secondary pectoral fin rays (usually 12); scaleless belly; pattern of keeled scales on anterior, dorsal portion of body consisting of a single central keel in the posterior third of each scale; 43-50 lateral line scales.

It also has 5-6 rounded dark blotches on the dorsal surface, and up to 8 along the lateral line which become larger towards the caudal fin. Roberts (1989) states that it has 5 dorsal blotches and 7-8 lateral blotches.

Originally described in Homaloptera, this species was placed in Balitoropsis by Kottelat (2012), but he subsequently (2013) followed Randall & Page (2012) and considered it in Homalopteroides.

The genus Homalopteroides was revalidated by Randall and Page (2012)[7] on the basis of its unique mouth morphology, 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)[10] 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.