Present investigation was carried out to assess the effect of flood on fishes of Garhwal Himalyas of Uttrakhand state, India. Three different sites (Rishiganga, Dhauliganga and Alaknanda) were sampled before (October 2020) and after flood (March 2021).We have primarily focused on fishes of order Cypriniformes, Mastacembelis and Ophiocephaliformes. In this paper, we explained how regular floods of river Ganga which occur due to sudden landslide and glacial lake outburst affect the fishes of upper Ganga region.