Humans altered the landscape according to their needs which is slowly becoming natural to artificial and wetlands are one of those. Wetlands are an important ecosystem for all kindsof aquatic floraand fauna. Weundertooka study to enumerate the bird and butterfly diversity of Ganga Lake which is a sacred lake of the Nyishi tribe of Arunachal Pradesh. In this study, a total of 59 species of birds belonging to 29 families and eight orders was recorded and 63 species of lepidopterans belonging to 10 families were recorded during the study. The area shelters rare/uncommon butterfly species like Athyma Kanwa, Neptis Radha, Neptis Magadha, Athymaranga, Neptis Miah and Melanitis Phedima. Locals also reported that the lake and surrounding area was very rich in faunal diversity earlier. According to the local community, bird and mammals species were killed from the area by hunting, because of which the fauna of the area began disappearing gradually. Habitat alteration for agriculture and the gradual expansion of local villages in the surrounding areas is negatively impacting the unique biodiversity of this sacred lake. This lake is an important habitat for birds and butterflies so strict conservation measures may help to restore the diversity of this sacred lake.