Indian Marsh Mongoose or Bengal Mongoose is now categorized as Endangered Species in India. The main threat is habitat (i.e. wetlands or marshy lands) loss. The East Kolkata wetlands may be the last habitat of this species. I was quite lucky to see that species in front of my eyes. I had managed to get a distant shot.
Canon 7D Mark II + Sigma 150-600 mm C
600 mm, 1/1250s, f/8, iso 400