Occurrence of exotic vermiculated sailfin catfish Pterygoplichthys disjunctivus from the lower stretch of River Ganga, West Bengal, India

The present study reports a record of invasive Loricariid catfish Pterygoplichthys disjunctivus (Weber, 1991) (Siluriformes: Loricariidae) from the Bhagirathi-Hooghly system of River Ganga in West Bengal, India. The species was encountered from Farakka and Balagarh regions of Ganga, two areas with different hydrological regimes. The average total length and total weight of the collected species was in the range of 360-450 mm and 314-545 g respectively. This exotic species is reported to contribute about 10% of the total catch from the Balagarh area of the river stretch, while its occurrence is sparse in Farakka. The algivorous nature of feeding can pose a threat to nativebottom dwelling fish due to feeding competition. As the presence of this exotic fish in the lower parts of Ganga has been confirmed, we discuss necessary management interventions like identifying the source of its introduction in order to prevent future threats from this invasive species to native river species.