Some aspects of ecology of endemic freshwater fishes of Sri Lanka

Abstract

Sri Lanka supports a diverse freshwater fishes, about 48% of which are endemic. Most of these endemic freshwater fish species occur in the hill country forested streams of the wet zone. There are sophisticated interactions between fish species in a fish community and its environment for food, space and/or spawning. As evident from the biology of cyprinids in hill streams in Sri Lanka, most of the endemic freshwater fish species tend to show well-defined niche segregation and ecological adaptations. Several anthropogenic activites such as deforestation, gem mining and uncontrolled use of agrochemicals, pose significant threats to survival of many endemic freshwater fish species in Sri Lanka. Exploitation of endemic fish species from the wild for ornamental fish trade is also a major cause of decline of their populations. Further, accidental introduction of clown knife fish (Chitala ornatus) and cleaner fish (Ptrygoplichthys multiradiatus), which poses threats to diversity of freshwater fishes in Sri Lanka, is an indirect adverse effect of ornamental fish trade. Although some introductions of exotic fish species such as African cichlids, most notably Oreochromis mossambicus and O. niloticus, have socio-economic benefits, effective strategies should be implemented to control transfer and introduction of aquatic organisms.