30% of the species originate from the sea and inhabit the delta areas. Among the economically important species are food fish such as Pangasius catfish, giant gourami, kissing gourami, snakeheads and large barbs (Leptobarbus, Puntioplites, Tor and others), and species from the aquarium trade such as the super red arowana and rasboras. Because of overfishing and habitat degradation, several species are threatened. Among these are the endangered arowana and white-edge freshwater whipray, and the wallago catfish, which formerly migrated in large groups in the Kapuas River. Part of the high species diversity in the Kapuas is related to the many different habitats in the river basin. In the headwaters are fast-flowing highland streams, typically dominated by small loaches, and small —often acidic (blackwater)— forest streams and peat swamps with species such as the tiny Sundadanio rasboras and macropodusine gouramis. The main river itself also includes several habitats, ranging from the nearshore to open waters. In the deepest sections, no light exists and in one species, Lepidocephalus spectrum, this has resulted in a complete reduction of both eyes and pigmentation (similar to cavefish). Owing to the warm climate and abundance of food, most fishes breed all through the year with only a few species like fire eel (Mastacembelus erythrotaenia) having certain reproduction periods. The number of individuals per species is relatively low. The large variety of species may be explained by the fact that some 6,000 years ago, the Kapuas River, as a tributary of the Sunda River, was connected to other tributary rivers of South Sumatra, Java and Malay Peninsula. Apart from fish, there are numerous crabs, prawns, water striders and other aquatic insects. The rich flora and fauna results in very complex food chains, with fishes consuming foods ranging from fruits to other fish. For example, Hemirhamphodon pogonognathus feeds exclusively on terrestrial insects. Abundant fruits and seeds enter the river after falling from large trees which bend over its waters. The feeding habits of the fish in the Kapuas River are distributed as follows: 54% are omnivores; 36% are carnivorous and eat other fish (14%), insects (5%) and mixed small forest animals (17%). The remaining 10% are herbivorous, with 4% of them specialising in algae. Transport and economic value The Kapuas River is the major waterway connecting the center of the island with its western coast. The large river width and depth (up to 27 meters) support intensive cargo