Aquarist Atlas
Barbs · Goldfish & coldwater cyprinids

Acheilognathus tonkinensis

(Vaillant, 1892)

Tonkin bitterling

Full synonymy (2)
  • Acanthorhodeus robustus Holčík 1972 · junior synonym
  • Acanthorhodeus tonkinensis Vaillant 1892 · original combination

Source: Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Van der Laan, eds.), California Academy of Sciences.

3 cited sourcesName checked against Eschmeyer’s Catalog of Fishes, update of

IUCNDATA DEFICIENT · 2010
DDnot on the EX–LC scale
CARESNOT LISTED
Type localityNam-kia River, affluent to River Noire, Upper Tonkin, northern Vietnamper Catalog of Fishes
Scientific size5 in12.2 cm total length
Depth—not recorded
DietGrazer; algae, small invertebrates and detritus
BreedingMussel spawner; eggs laid inside freshwater bivalves
Sexual dimorphismYesFemales develop an ovipositor in the breeding season
PhotographsSee photosGoogle Images →

Acheilognathus tonkinensis is a bitterling of northern Vietnam, southern China and Laos that FishBase gives at 5 in TL. Vaillant described it in 1892 from the Nam-kia River.

What's in the name

Acheilognathus tonkinensis — ah-kay-log-NAY-thus ton-kin-EN-sis

Acheilognathus
  • a-Greek — without
  • cheilosGreek — lip
  • gnathosGreek — jaw
tonkinensis
  • Tonkinplace name — the Tonkin region of northern Vietnam
  • -ensisLatin — of or from

Taxonomy & naming

Vaillant described the species in 1892 from the Nam-kia River, a tributary of the Black River in Upper Tonkin, northern Vietnam. It belongs to the bitterlings, family Acheilognathidae.

Morphology

A deep-bodied, laterally compressed bitterling. FishBase gives a maximum of 5 in TL. Females carry a long ovipositor in the breeding season.

Habitat

FishBase lists it as a freshwater, benthopelagic, tropical fish of northern Viet Nam, southern China and the Nam Mat basin in Laos. Bitterlings live in slow water where freshwater mussels occur.

Feeding

Bitterlings graze algae, small invertebrates and detritus. The diet of this species has not been described specifically.

Mating

As in other bitterlings, males hold territories around mussels and court females there.

Breeding

FishBase notes that the female uses an ovipositor to place eggs inside bivalves, and the young stay in the bivalve until they can swim. Breeding therefore needs live freshwater mussels.

In the aquarium

It suits a planted tank with a sandy bottom and a few mussels if breeding is wanted. Husbandry details beyond this are not recorded for this species.

Conservation

IUCN lists the species as Data Deficient, assessed in 2010, so its population status is not known.

Common questions

Tonkin bitterling (Acheilognathus tonkinensis): how big does it get?
Up to 5 in total length (TL).
Tonkin bitterling (Acheilognathus tonkinensis): where does it come from?
It is recorded from Vietnam, China and Laos.

Related species compared · Acheilognathus

SpeciesAdult sizeTemperaturepHHardnessIUCN
Tonkin bitterlingAcheilognathus tonkinensisthis species5 in TL———DD
Giant bitterlingAcheilognathus macropterus11 in SL59–77 °F——DD

Recorded ranges from each species’ own page; hardness is the tolerance its sources give, not a measurement of the water it lives in.

Also from the Red River basin

Sources

  1. Eschmeyer's Catalog of Fishes — Acheilognathus tonkinensis (Vaillant, 1892)
  2. FishBase — Acheilognathus tonkinensis
  3. IUCN Red List — Acheilognathus tonkinensis

Naming authority: Acheilognathus tonkinensis in Eschmeyer’s Catalog of Fishes ↗

Last reviewed 2026-10-05.

How to cite

Aquarist Atlas (2026). Acheilognathus tonkinensis. Aquarist Atlas.https://www.aquaristatlas.com/barbs/acheilognathus-tonkinensis/

Add this species card to your site

Paste this into a product listing, club page or blog post. It shows this species’ size, water ranges and conservation status, kept current from the atlas, with a link to this page. Free to use; keep the link intact, as it is the attribution. How the card works.

<div data-atlas="species/acheilognathus-tonkinensis"><a href="https://www.aquaristatlas.com/barbs/acheilognathus-tonkinensis/">Tonkin bitterling (Acheilognathus tonkinensis) on Aquarist Atlas</a></div>
<script src="https://www.aquaristatlas.com/embed/v1/card.js" async referrerpolicy="no-referrer"></script>

Where it has been recorded

26 georeferenced records (GBIF). Each point is a field observation or museum specimen — pan and zoom to explore where this species turns up. The coordinates come straight from GBIF and are often rounded or tied to the nearest town or river landing, so a dot can sit just beside the actual water rather than in it.

← All barbs