Status of alien fish species in the Western Ghats (India) as revealed from 2000-2004 surveys and literature analyses

The objective of this study was to provide an inventory on alien fish species based on literature analysis and sampling surveys over 4 similar to years, covering 465 locations of 25 river systems in Western Ghats, India. Thirty-two species of seven orders and 10 families have so far been recorded in the published literature as alien fishes in the Western Ghats. Cyprinidae encompassed the largest number of species with 14 members, followed by Poeciliidae with four and Channidae with three members. Nineteen alien fish species were delineated during the fish inventory surveys, of which the freshwater garfish Xenentodon cancila, snakehead murrel Channa striata and Mozambique tilapia Oreochromis mossambicus far exceeded other species in the number of river systems (23, 20 and 15 respectively) and locations (29, 26 and 24 respectively) where the species were encountered. Pool and reservoir habitats exhibited the highest distribution of alien fishes. Oreochromis mossambicus (pool, run, riffle and reservoir) and Poecilia reticulata (pool, run, cascade and reservoir) were found in the highest number of habitats. The results demonstrate that alien fishes have extensively colonized the river systems in the Western Ghats. A comprehensive risk assessment to ascertain the potential impacts of the alien fishes is very necessary to formulate appropriate management plans for control of alien fish invasions and conserve native fishes in the Western Ghats.The objective of this study was to provide an inventory on alien fish species based on literature analysis and sampling surveys over 4 similar to years, covering 465 locations of 25 river systems in Western Ghats, India. Thirty-two species of seven orders and 10 families have so far been recorded in the published literature as alien fishes in the Western Ghats. Cyprinidae encompassed the largest number of species with 14 members, followed by Poeciliidae with four and Channidae with three members. Nineteen alien fish species were delineated during the fish inventory surveys, of which the freshwater garfish Xenentodon cancila, snakehead murrel Channa striata and Mozambique tilapia Oreochromis mossambicus far exceeded other species in the number of river systems (23, 20 and 15 respectively) and locations (29, 26 and 24 respectively) where the species were encountered. Pool and reservoir habitats exhibited the highest distribution of alien fishes. Oreochromis mossambicus (pool, run, riffle and reservoir) and Poecilia reticulata (pool, run, cascade and reservoir) were found in the highest number of habitats. The results demonstrate that alien fishes have extensively colonized the river systems in the Western Ghats. A comprehensive risk assessment to ascertain the potential impacts of the alien fishes is very necessary to formulate appropriate management plans for control of alien fish invasions and conserve native fishes in the Western Ghats