
Photo: Vsevolod Rudyi · CC BY 4.0 (May be cropped or resized)
Lutra lutra
Size
Length 57–95cm; tail 35–45cm
Weight
Usually 7–12kg; up to 17kg
The Eurasian otter is normally 57 to 95cm long, not counting a tail of 35 to 45cm, and averages 7 to 12kg, though a large old male may reach 17kg. Pups stay dependent on the mother for around 13 months. The largest reported specimen, from a source considered reliable but not verified, weighed over 24kg (Wikipedia, general species account).
The Mammal Diversity Database lists it in 74 countries, Bhutan among them. The sources opened give no Bhutan-specific records, diet or habitat detail, so none is stated.