Microcobitis misgurnoides (RENDAHL, 1944)

SynonymsTop ↑

Cobitis misgurnoides Rendahl, 1944; ? Cobitis nuicocensis Nguyen & Vo, in Nguyen, 2005

Etymology

Microcobitis: from the Greek word micros, meaning ‘small’ (used as a prefix in this case) and the generic name Cobitis, type genus of Cobitidae, in which Microcobitis was originally placed due to the similar shape of the lamina circularis in males.

Classification

Order: Cypriniformes Family: Cobitidae

Distribution

Described from a lake known as Thua Luu, south of the city of Da Nang, Vietnam and since recorded from various river basins in central regions of the country.

It’s also said to occur in some rivers of eastern Laos which drain the western Annamite mountain range and form part of the Mekong River system.

Maximum Standard Length

35 – 41 mm.

Aquarium SizeTop ↑

A tank with base dimensions of 45 ∗ 30 cm or more should prove adequate.

Maintenance

Likely to prefer a soft, sandy substrate with other décor not essential provided some cover is available.

A natural-looking set-up could include water-worn rocks or driftwood branches or tree roots – add these prior to the substrate to prevent them being toppled by digging activity.

Lighting can be quite dim unless you intend to grow plants, and a few handfuls of leaf litter would complete the natural effect.

Provided oxygenation is adequate the level of water movement should be unimportant although this species is also likely to do well in a river-style set-up.

Like many fishes that hail from pristine envioronments it’s probably intolerant to accumulation of organic wastes and likely to require spotless water in order to thrive.

For this reason it should never be introduced to biologically immature set-ups, and weekly water changes of 30-50% tank volume should be considered routine.

Water Conditions

Temperature: 20 – 24 °C

pH: 5.5 – 7.0

Hardness: 18 – 179 ppm

Diet

Little is known of this species‘ natural diet although presumably it feeds on small crustaceans, insect larvae and other invertebrates.

In the aquarium it’s proven to accept both dried foods and live or frozen Artemia nauplii, Cyclops, etc., but anything offered must be of a sufficiently small grade.

Behaviour and CompatibilityTop ↑

Should do well alongside fishes that inhabit the upper part of the water column such as most Danio, Devario, Laubuca and many Rasbora species.

The presence of these should also make it less timid as the absence of schooling fishes is often used as a signifier for approaching danger in nature.

Many sand-dwelling loaches from the families Botiidae, Cobitidae and Nemacheilidae are also suitable tankmates but proper research is essential as some can be excessively territorial or otherwise aggressive.

It’s apparently gregarious so best kept in a group of six or more though will probably do ok when maintained in small numbers, and we very much doubt that it will exhibit any aggression towards conspecifics or other tankmates.

Sexual Dimorphism

Adult females are typically heavier-bodied and a little larger then males.

In mature males the second pectoral-fin ray is extended and there is a thickened structure known as the lamina circularis at the base, which in M. misgurnoides resembles the ‘axe-shaped’ form seen in some Cobitis species but differs by being more oval in shape and posessing a relatively ‘free’ short section that isn’t connected to the fin ray (length of ‘free’ section fits 4-5 times into length of connected section, vs. 0.8-2 times in Cobitis spp.).

Reproduction

Presumably a seasonal spawner in nature but hasn’t been bred in captivity as far as we know.

NotesTop ↑

This species was initially described as a member of Cobitis and remained as such for over 60 years until being redescribed in the new genus Microcobitis by Bohlen and Harant (2011).

Microcobitis can be separated from Cobitis by a number of characters including: small adult size (to 41 mm SL); possession of a shorter (29-40% of head length) and more rounded snout than most Cobitis spp.; body pattern consists of a midlateral row of brown blotch-like markings plus a further, poorly-defined row along the dorsal surface with additional, irregularly-distributed markings between these rows; lower lip divided into four, barbel-like projections; 35-36 vertebrae. We don’t think it’s appeared in the aquarium trade to date.

The family Cobitidae, often referred to as ‘true’ loaches, is widely-distributed across most of Eurasia with the Indian subcontinent, Southeast Asia and China representing particular centres of species diversity.

Phylogenetic analyses by Tang et al. (2006), Šlechtová et al. (2007) and Šlechtová et al. (2008) revealed that the group constitutes a separate genetic lineage to the family Botiidae (the two were previously grouped together under Cobitidae as subfamilies Cobitinae and Botiinae).

Microcobitis currently represents one of four generalised lineages within a ‘northern’ clade of the family Cobitidae comprising species distributed in Europe, western, northern and eastern Asia, Vietnam and Laos. These are as follows:

1) All species of Sabanjewia.
2) Microcobitis misgurnoides.
3) All Misgurnus, Paramisgurnus and Koreocobitis spp.
4) All Cobitis spp. plus Iksookimia, Niwaëlla and Kichulchoia spp.

All cobitids possess sharp, motile, sub-ocular (below the eye) spines which are normally concealed within a pouch of skin but erected when an individual is stressed, e.g., if removed from the water. Care is therefore necessary as these can become entangled in aquarium nets and, in larger species, break human skin.

References

1. Bohlen, J. and R. Harant, 2011 - Ichthyological Exploration of Freshwaters 21(4): 295-300
   Microcobitis, a new genus name for Cobitis misgurnoides (Teleostei: Cobitidae).
2. Kottelat, M., 2012 - Raffles Bulletin of Zoology Supplement 26: 1-199
   Conspectus cobitidum: an inventory of the loaches of the world (Teleostei: Cypriniformes: Cobitoidei).
3. 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).
4. Šlechtová, V., J. Bohlen and A. Perdices, 2008 - Molecular Phylogenetics and Evolution 47(2): 812-831
   Molecular phylogeny of the freshwater fish family Cobitidae (Cypriniformes: Teleostei): delimitation of genera, mitochondrial introgression and evolution of sexual dimorphism.
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.