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?Annamia thuathienensis NGUYEN, 2005


Annamia: named for Annam, the old name for the region now comprising central Vietnam.

thuathienensis: named for Thua Thiên Province, Vietnam, where this species was discovered.


Order: Cypriniformes Family: Gastromyzontidae


Described from the Bô River, Thua Thien-Hue Province, central Vietnam, and there are no additional records.


Unknown but its ecology should be similar to that of A. normani which inhabits shallow, swiftly-flowing stretches of streams and small rivers.

These are characterised by crystal clear water, and these loaches tend to be restricted to riffles, rapids, and swiftly-flowing runs with rocky substrates.

In one study adults were found to live in rapids, feeding selectively on cyanobacteria (see ‘Diet’), whereas juveniles occupied shallower water grazing organic detritus.

Maximum Standard Length

80 – 100 mm.

Aquarium SizeTop ↑

Minimum base dimensions of 120 ∗ 30 cm or equivalent are required.


Since Annamia spp. are obligate residents of riffles and rapids in nature it is essential to maintain them in a set-up designed to resemble such a habitat.

Use a substrate of gravel, sand (or a mixture), and add a layer of variably-sized water-worn rocks and boulders plus some driftwood roots or branches if you wish. While the majority of aquatic plants will fail to thrive in such surroundings, hardy genera such as Microsorum, Bolbitis, or Anubias can usually be grown attached to the décor, while bright lighting will promote the growth of aufwuchs upon which the fish will graze.

Like many species that naturally inhabit running waters they are intolerant to the accumulation of organic waste, and requires spotless water in order to thrive. High levels of dissolved oxygen and water movement are also essential with a recommended turnover of 10-15 times per hour, meaning additional powerheads, airstones, etc., should be employed as necessary.

Since stable water conditions and the presence of biofilm are obligatory for their well-being these fish should never be added to biologically-immature aquaria, and weekly water changes of 30-50 % aquarium volume should be considered mandatory.

Water Conditions

Temperature: 16 – 22 °C

pH: 6.0 – 7.5

Hardness: 18 – 179 ppm


Traditionally considered to be a micropredator feeding on insect larvae and suchlike (Rainboth, 1996), but a study by Herder and Freyhof (2006) revealed adult A. normani inhabiting the Duc My River in central Vietnam to be specialised grazers of cyanobacteria. In rapids the latter form hard encrustations on rock surfaces from which adults are able to bite chunks.

Whether this behaviour is only representative of A. normani, or even restricted to particular populations, is unclear but it would seem wise to offer dried foods containing Spirulina or similar alongside chironomid larvae (bloodworm), Tubifex, Artemia, etc., and ideally allow aufwuchs to grow on all surfaces in the tank except the viewing pane.

Gastromyzontids are often seen on sale in an emaciated state which can be difficult to correct. A good dealer will have done something about this, but if you decide to take a chance with specimens in which the body appears narrowed, especially between the pectoral and pelvic fins, they will need a constant supply of suitable foods and should be kept alone until strong enough to compete with other species.

Behaviour and CompatibilityTop ↑

Largely peaceful, although its environmental requirements limit the choice of suitable tankmates somewhat. Species inhabiting similar environments include Barilius, OpsariusDischerodontus, Garra, larger Devario, some Rasbora, Rhinogobius, Sicyopterus and Stiphodon gobies, plus catfishes from genera such as Glyptothorax, Akysis, and Oreoglanis.

Many loaches from the families Nemacheilidae, Balitoridae, and Gastromyzontidae are also suitable, although squabbles may occur with the latter group in particular.

Annamia are found living in large aggregations in nature so a group of eight or more should be considered the minimum purchase. When kept singly or in smaller numbers they tend to be quite shy.

Sexual Dimorphism

Sexually mature females are likely to be a little larger and fuller-bodied than males.


Presumably a seasonal spawner in nature but has not been bred in captivity.

NotesTop ↑

A. thuathienensis was described in Vietnamese and very little is known about it. Some major resources fail to list it as valid, and it is considered a species inquirenda by Kottelat (2012).

Annamia spp. may be confused with related genera such as those of the genus BalitoropsisThey can be identified by their more depressed body shape, elongate lower caudal-fin lobe, and the presence of a single unbranched ray in the pectoral and pelvic fins. At least one undescribed member of the genus is thought to exist.

The family Gastromyzontidae is currently considered valid following Kottelat (2012).

It contains a number of genera which had formerly been included in several families and subfamilies, most recently Balitoridae, of which the most well-known in the aquarium hobby include Beaufortia, Formosania, Gastromyzon, Pseudogastromyzon, Hypergastromyzon, Liniparhomaloptera, Sewellia and Vanmanenia.


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