Rhinogobius leavelli (HERRE, 1935)

SynonymsTop ↑

Ctenogobius leavelli Herre, 1935

Etymology

Rhinogobius: from the Greek rhinos, meaning ‘nose’, and the generic name Gobius.

Classification

Order: Perciformes Family: Gobiidae

Distribution

Widely distributed from the Nam Ma and Nam Mat river systems in northeastern Laos throughout northern Vietnam, including the Red (Hóng Hé) River, to the Pearl (Zhu Jiang) drainage in Guangxi Zhuang Autonomous Region, southern China.

Type locality is given as ‘Hill streams around Wuchow, Kwangsi Province, China’, which probably corresponds to the city of Wúzhōu in Guangxi.

Wúzhōu lies at the confluence of the Gui and Xun rivers which subsequently form the Xi River, a western tributary of the Pearl system.

Maximum Standard Length

50 – 60 mm.

Aquarium SizeTop ↑

An aquarium with base dimensions of 60 ∗ 30 cm is large enough to house a small group.

Maintenance

Not difficult to maintain under the correct conditions; we strongly recommend keeping it in a tank designed to simulate a flowing stream with a substrate of variably-sized rocks, sand, fine gravel, and some water-worn boulders.

This can be further furnished with driftwood branches, terracotta pipes, plant pots, etc., arranged to form a network of nooks, crannies, and shaded spots, thus providing broken lines of sight.

While the majority of aquatic plants will fail to thrive in such surroundings hardy types such as Microsorum, Bolbitis, or Anubias spp. can be grown attached to the décor.

Like many fishes that naturally inhabit running water it’s intolerant to accumulation of organic pollutants and requires spotless water in order to thrive, thus weekly water changes of 30-50% tank volume should also be considered routine.

Though torrent-like conditions are unnecessary it does best if there is a high proportion of dissolved oxygen and some water movement in the tank meaning power filter(s), additional powerhead(s), or airstone(s) should be employed as necessary.

Water Conditions

Temperature: 20 – 28 °C

pH: 6.0 – 8.0

Hardness: 36 – 268 ppm

Diet

Rhinogobius spp. tend to be opportunistic carnivores feeding on a range of small invertebrates, crustaceans and similar in nature.

In the aquarium they should be offered small live or frozen foods such as chironomid (bloodworm) or mosquito larvae, Artemia, Daphnia, Mysis, etc.

Dried foods may be accepted following a period of acclimatisation but should not be used regularly.

Behaviour and CompatibilityTop ↑

This is a robust species but it can be kept in a community provided tankmates are chosen with care.

Peaceful, pelagic species which inhabit similar environments in nature such as Tanichthys or Danio species are perhaps the best choices for the upper levels, but we’ve also seen Rhinogobius spp. being maintained alongside barbs, small characins, poeciliid livebearers, etc.

Less suitable are freshwater shrimp from genera such as Caridina and Neocaridina as these are likely to be predated upon.

Balitorid and nemacheilid loaches may prove suitable in larger tanks but in smaller set-ups R. leavelli should ideally be the only benthic species included.

It should not mixed with congeners, especially closely-related ones such as R. nantaiensis, since it’s not yet clear if they’re capable of hybridisation.

Larger fishes are best omitted although in very large set-ups it may be possible to add a few non-predatory, surface-dwelling ones, while the majority of cichlids and other territorial fishes inhabiting the lower reaches should be avoided entirely.

While males are territorial with one another to an extent serious damage is unlikely provided the tank contains sufficient cover, and in fact they appear to actively require the presence of conspecifics.

Aim to purchase at least two males and as many or more females or the fish may become listless and inactive.

Sexual Dimorphism

Males are more colourful than females and in most cases develop more extended dorsal and anal fins rays as they mature.

Reproduction

Some wild populations of this species have evolved a complex amphidromous breeding strategy in which adults live and spawn in freshwater or brackish streams and the pelagic post-hatch larvae are washed downstream to the sea where the post-larval fry spend the first part of their life developing in estuarine nursery zones under brackish to full marine conditions.

Once they reach a certain stage of development they begin to migrate upstream with some moving into freshwater tributaries and others remaining in lower, tidally-influenced habitats.

Those exported for the aquarium trade to date appear to be entirely freshwater, however.

It may be that these do not all represent the same species but this has not yet been studied in detail (see ‘Notes’).

In nature the fish are reproductively active from summer to early autumn and during this period males begin to defend territories which tend to be centred around a flattish rock or stone beneath which the eggs are deposited, so it’s essential to provide such rocks in the breeding tank.

The eggs are very small compared with many congeners and 3000-4000 may be deposited by a single female.

Post-spawning the female is ejected and the male assumes responsibility for brood care and guarding.

Incubation is normally 3-4 days and the larvae drift in the water column for 24 hours or so post-hatching, after which they begin to move with a greater sense of direction.

Initial food needs to be very small with even freshwater rotifers proving too large and it can be almost a month until they’re able to accept Artemia nauplii and suchlike.

NotesTop ↑

This species appears to exist in a number of different forms which exhibit differences in colour pattern, morphology, or both, and it’s currently unclear whether all of them are truly conspecific or not although those in the aquarium trade all appear similar to one another.

We’ve been unable to obtain a copy of the original description so it’s not currently possible to provide a detailed diagnosis either, with most recent studies stating only that R. leavelli has more pectoral fin rays than the majority of congeners with at least 18, vs. 18 or less, plus 10-16 predorsal scales and a dark vertical bar at the base of the pectoral fin.

Fish identified as R. leavelli also tend to possess an orange blotch at the base of the caudal-fin which appears to be a character shared only with R. gigas among the species available in the trade at time of writing.

The Gobiidae is the most speciose vertebrate family and notoriously problematic in terms of identifying fishes down to species level.

Within this sizeable assemblage Rhinogobius is often included in the subfamily Gobionellinae alongside genera such as Brachygobius, Chlamydogobius, Mugilogobius, Pseudogobiopsis, Schismatogobius, and Stigmatogobius.

Members can be told apart from these and all other gobiid genera by the following combination of characters: head with four simple, longitudinal infraorbital sensory papilla rows a, b, c, and d, single cp papilla, and paired papillae in mental row f; head canal variable from complete loss to normal development of anterior and posterior oculoscapular canals, and preopercular canals, and always with double interorbital pores λ if the pore is present; body mostly covered with ctenoid scales; longitudinal scale series 25–42; head including cheek, snout, opercle, anterior part of nape as well as pre-pectoral region all naked; D1 usually VI; D2 I, 6–11; A I, 5–11; P 14–23; and V I, 5 + I, 5, forming a rounded disc with frenum present, performing two pointed spinous lobes, the spinous ray usually longer than the first branched ray; dorsal pterygiophore formulae modally 3–22 1 101; vertebrae 25–29, usually 26 for most landlocked species.

The genus is widely-distributed throughout much of continental Asia in Russia, Korea, China, Vietnam, Laos, Cambodia, and Thailand, plus numerous islands of the Western Pacific including Japan, Taiwan, Hainan, and the Philippines.

There currently exist over 60 recognised species with many more awaiting formal description, and a number of the described ones are only considered nominal taxa pending additional study.

Those exhibiting similarities in appearance, morphology and behaviour are therefore often aggregated in nominal species groups, e.g., the R. brunneus group, R. duospilus group, etc., for ease of reference.

The fused pelvic fins form a structure normally referred to as the ‘pelvic disc’, a common feature among gobiids which is used to adhere to rocks and other submerged surfaces.

Rhinogobius spp. also exhibit different reproductive strategies depending on environment, with those inhabiting rivers connected directly to the sea typically amphidromous, and those landlocked in upper reaches of rivers or lakes non-diadromous.

Many of those appearing in the aquarium trade have proven difficult to identify for a number of reasons including:

– taxonomic confusion.
– lack of aquarium literature.
– incorrect labelling by exporters and subsequently shops.
– historical over-use of some names, e.g., ‘Rhinogobius wui‘ which is itself an invalid synonym of R. duospilus.
– likely trade of undescribed species without locality data.
– mixing of species at export facilities.

Thanks to Jutta Bauer.

References

1. Chen, I-S. and M. Kottelat, 2005 - Journal of Natural History 39(17): 1407-1429
   Four new freshwater gobies of the genus Rhinogobius (Teleostei: Gobiidae) from northern Vietnam.
2. Chen, I-S. and P. J. Miller, 2008 - The Raffles Bulletin of Zoology Supplement 19: 225-232
   Two new freshwater gobies of genus Rhinogobius (Teleostei: Gobiidae) in southern China, around the northern region of the South China Sea.
3. Huang, S.-P. and I-S. Chen, 2007 - The Raffles Bulletin of Zoology Supplement 14: 101-110
   Three new species of Rhinogobius Gill, 1859 (Teleeostei: Gobiidae) from the Hanjiang Basin, southern China.
4. 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.
5. Kottelat, M., 2001 - WHT Publications, Colombo: 1-198
   Fishes of Laos.