An exotic catfish was recorded at Madampa Lake in Southwest coastal zone of Sri Lanka during an ichthyofaunal survey carried out from 1st of April 2009 to 20th August 2010. The species is identified as Pangasianodon hypophthalmus, which has been described as a potentially problematic species on native fishes in some neighbouring countries of the region. This species naturally occurs in the Mekong River in South-East Asia. The observation of P. hypophthalmus is a novel record in wild habitats of Sri Lanka, where its introduction is probably an accidental release from the ornamental fish trade, but no substantial information is detected as a proof of invasion or a naturalisation of the current population.