Major Habitat Type
Tropical and subtropical coastal rivers
Drainages flowing into
Gulf of Tonkin
Main rivers to other water bodies
Cả River (Lam River), Gianh River
This ecoregion includes basins that drain the eastern slopes of the Annamite Range in Vietnam from north of the Deo Hai Van Pass to the Gianh River basin.
This ecoregion comprises several terrestrial ecoregions, including the Luang Prabang montane rain forests, Northern Indochina subtropical forests, Northern Annamites rain forests, and Northern Vietnam lowland rain forests (Wikramanayake et al. 2002).
Description of endemic fishes
The ecoregion contains 23 recorded endemic species, including a number of endemic species of the genus Schistura.
Justification for delineation
For Southeast Asia, delineations were determined using a bottom-up approach that employed both published and unpublished field data and expert assessment (Abell et al. 2008; Kottelat 1989). The available data makes it difficult to determine the exact northern boundary of this ecoregion. Basins south of the Deo Ha Van Pass have more faunistic affinities with the Mekong and Southeast Asia, whereas the basins of this ecoregion have more affinities with the Song Hong  and Xi Yiang  ecoregions. It includes several extensive karstic areas with underground systems (M. Kottelat pers. comm. 2006).
- Abell, Robin,M.L. Thieme,C. Revenga,M. Bryer,M. Kottelat,N. Bogutskaya,B. Coad,N. Mandrak,S.C. Balderas,W. Bussing,M.L.J. Stiassny,P. Skelton,G.R. Allen,P. Unmack,A. Naseka,R. Ng,N. Sindorf,J. Robertson,E. Armijo,J.V. Higgins,T.J. Heibel,E. Wikramanayake, (2008). "Freshwater Ecoregions of the World: A New Map of Biogeographic Units for Freshwater Biodiversity Conservation" BioScience 58 (5) pp. 403-414.
- Wikramanayake, Eric,Dinerstein, Eric,Loucks, C.,Olson, D.M.,Morrison, J.,Lamoreux, J. L.,McKnight, M.;Hedao, P. (2002). "Terrestrial ecoregions of the Indo-Pacific: A conservation assessment" Washington, DC: Island Press.
- Kottelat, M. (1989). "Zoogeography of the fishes from Indochinese inland waters with an annotated check-list" Bulletin Zoologisch Museum Universiteit van Amsterdam 12 (1) pp. 1-54.