Indian Ocean Slope of Sumatra & Java




J. Hales



Major Habitat Type

Tropical and subtropical coastal rivers

Drainages flowing into

Indian Ocean

Main rivers to other water bodies

The ecoregion’s water bodies include small coastal rivers and lakes. One of the largest lakes in the ecoregion is Maninjau.



This ecoregion spans the small, southwestern coastal basins along the Indonesian islands of Sumatra and Java. It also includes the islands of Simeulue, Nias, Siberut, Mentawai Islands, and Enggano off the coast of Sumatra. 


The ecoregion lies west-southwest of the volcanic chain of mountains that form the spine of Sumatra and Java. These include the Barisan Mountains in Sumatra; Mount Semeru, the highest mountain in Java; as well as Krakatau, located in the Sunda Strait between Sumatra and Java.

Freshwater habitats

The ecoregion comprises small coastal basins with short streams.

Terrestrial habitats

This ecoregion spans several terrestrial ecoregions, including Sumatran lowland rain forests, Mentawai Islands rain forests, Western Java rain forests, and Eastern Java-Bali rain forests (WWF 2001).

Description of endemic fishes

The number of endemics is estimated to be around 20, and includes endemic Cyprinidae (e.g. Rasbora reticulate, R. jacobsoni) and Gobiidae (genera Sicyopterus, Sicyopus, Stiphodon) (M. Kottelat pers. comm. 2006).

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For Southeast Asia, delineations were determined using a bottom-up approach that employed both published and unpublished field data and expert assessment (Abell et al. 2008; Kottelat & Whitten 1993; Koumans 1953; Weber & Beaufort 1915). The ecoregion has a depauperate Sundaic fish fauna with a few endemic Cyprinidae (e.g. Rasbora reticulata, R. jacobsoni) and many marine species entering freshwaters, including several endemic Gobiidae (genera Sicyopterus, Sicyopus, Stiphodon) (M. Kottelat pers. comm. 2006).


  • World Wildlife Fund (WWF) (2001) \Terrestrial Ecoregions of the World\ "<"">"
  • Koumans, F. P. (1953). "Gobioidea" Weber, M. ;L. F. de Beaufort (Ed.) Fishes of the Indo-Australian Archipelago ( (Vol. 10, pp. 1-423 ) Leiden: E. J. Brill,.
  • Weber, M. and Beaufort, L. F. D. (1915). "Les Poissons d'eau douce de la Nouvelle-Cal√©donie" F. Sarasin and J. Roux (Ed.) Nova Caledonia Zoologie ( pp. 17-41 ) 2 (1). C. W. Kreidels Verlag, Wiesbaden:
  • Kottelat, M.,Whitten, A. J.,Kartikasari, S. N.;Wirjoatmodjo, S. (1993). "Freshwater fishes of Western Indonesia and Sulawesi" Hong Kong: Periplus.
  • 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.