Rhinogobius chiengmaiensis
Chiangmai Stream Goby
Etymology
Rhinogobius: from the Greek rhinos, meaning ‘nose’, and the generic name Gobius.
chiengmaiensis: named for Chiang Mai (also written Chiengmai) province in northern Thailand, type locality of this species.
Classification
Order: Perciformes Family: Gobiidae
Distribution
Known only from the middle-and-upper Chao Phraya river system in central Thailand including its major tributaries the Ping and Nan rivers.
Type locality is ‘Chieng Mai, northern Thailand’.
Habitat
Inhabits smaller rivers, tributaries and streams with substrates of gravel, rocks, boulders, and exposed bedrock which undergo seasonal variations in water flow rate, depth and turbidity.
Aquatic plants are not normally a feature of such habitats although riparian and overhanging vegetation may grow thickly.
Maximum Standard Length
40 – 50 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. 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: 18 – 26 °C. It can temporarily withstand warmer conditions provided dissolved oxygen levels are maintained.
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 ↑
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.
It should not mixed with other Rhinogobius spp. since it’s not yet clear if they’re capable of hybridisation, but other stream-dwelling gobies from genera such as Stiphodon, Sicyopterus, Sicyopus or Schismatogobius spp. generally make good companions.
Less suitable are freshwater shrimp from genera such as Caridina and Neocaridina as these are likely to be predated upon.
Other bottom-dwellers can include diminutive loaches from genera such as Gastromyzon, Pseudogastromyzon, or Acanthopsoides, and in high-turnover set-ups obligate torrent-dwellers like Annamia, Homaloptera, etc. Avoid those that feed aggressively or are excessively territorial, e.g., many Schistura spp.
Larger fishes are best omitted although in very large set-ups it may be possible to add a few non-predatory, surface-dwelling ones.
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
Adult males are more intensely-coloured and develop slightly more-extended dorsal and anal fins than females.
Reproduction
In nature reproduction occurs from May to August in summer and December to March in winter, though in aquaria it can be bred year-round and is among the less-problematic members of the genus to breed.
As is typical for the genus eggs are deposited on the ceiling of a cave or crevice and guarded by the male until hatching.
Several potential sites should be offered in the form of rocks (flat slate tends to be easiest to handle, see below), terracotta pipes, plant pots, etc.
A nuptial male will select a site and defend it against other males, but if one is not available may excavate a cave beneath a rock or other piece of décor.
Spawning occurs secretively within the cave, and is usually signified by the pair disappearing from sight for an extended period of time.
They may remain inside for 2-3 days with the female ejected once spawning is complete, and should not be disturbed during this period.
Once the female is seen outside the cave, you can check for eggs by carefully lifting and tilting it without removing from the water.
Inexperienced pairs or males may eat the eggs, attach them poorly, or only partially fertilise them, but after a few attempts normally get things right.
At this point it’s advisable to remove all other fish except the male, or remove male and eggs elsewhere ( a small plastic container can be used to do so without harming either).
Brood size is normally between 20-60 depending on the age and experience of the fish and the eggs are relatively large as with other fluvial members of the genus.
Incubation is normally 9-11 days and there is no pelagic stage, the fry hatching with a relatively large yolk sac attached.
They can be offered Artemia nauplii, microworm, and suchlike immediately.
NotesTop ↑
This species has been exported for the ornamental trade but often labelled as the congener R. mekongianus.
Although the two do appear relatively similar R. chiengmaiensis can be identified by a combination of external characters including: presence of 5 irregular dark markings on the body (vs. 7-8 in R. mekongianus); branchiostegal membrane with tiny yellow to orange spots less than ½ pupil size (vs. branchiostegal membrane with relatively large spots about ⅔ pupil size); cheek and opercle with about 55–80 round dark spots in male (vs. around 40 round spots).
It’s also very similar to R. nammaensis from Laos but can be told apart from it by possession of 30 (vs. 32) longitudinal (lateral) scale rows, 3-4 (vs. 5-6) predorsal scales and presence (vs. absence) of two short, brown cross bars on the nape.
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.
References
- Chen, I-S., Y.-H. Cheng, and K.-T. Shao, 2008 - Ichthyological Research 55(4): 335-343
A new species of Rhinogobius (Teleostei: Gobiidae) from the Julongjiang basin in Fujian Province, China. - Fowler, H. W., 1934 - Proceedings of the Academy of Natural Sciences of Philadelphia v. 86: 67-163
Zoological results of the third De Schauensee Siamese Expedition, Part I - Fishes.
