Its not a Mystus gulio, the adipose fin is too long.
I would be inclined to go with Mystus castaneus myself, the prominant lateral line and pearling behind the gill plates match though the over all colour doesnt, but that could change as the fish settles in. From some reading it "could" be a Mystus armatus, but this is a previously rarely imported fish, however there have been a lot of Indian fish coming into the trade recently as collectors have been traveling further and further into southern india.