Bhutan is located in the eastern part of the Himalayas and has five major and 2 minor river basins. The total length of rivers and their tributaries is estimated to be about 7,200 km. Bhutan also has over 590 natural lakes of various sizes, most of them located above an altitude of 2,200 m. Bhutan’s rich water resources are being used for many developmental activities including hydropower constructions. Besides this, they are also being used for fish production. Therefore, in order to ensure that resources are being utilized sustainably, it is important that a good management plan be put in place. But in order to do that, it is imperative that a well researched fishery data be first developed (Kapetsky, 2007) as there is no proper database on the fishery resources as of now (Petr, 1999; Dhendup, 2011; MHPA 2011; PHPA, 2011).

Even though the technical and scientific capacity exists in a number of institutions (Funge-Smith, 2013), the fish fauna of the country has not yet been properly assessed and the existing records only show 50 freshwater fish species (BAP, 2009). Few independent studies have been taken up in the past, but a comprehensive study has still not been carried out to assess species composition and distribution of fish in Bhutan’s rivers. Therefore, the National Research Centre for Riverine & Lake Fisheries guided by the Department of Livestock, took up a study to assess fish fauna both in terms of species composition and distribution in Bhutan’s major river system. The Bhutan Trust Fund for Environmental Conservation funded the study.

Since it was difficult to study all the river system of Bhutan in a three years’ time, only three major river systems, namely the Amochhu/Torsa River, the Wangchhu River and the Punastangchhu/Sunkosh River were studied in this project. The study covered water bodies draining through 9 Dzongkhags, viz., Thimphu, Paro, Haa, Chukha, Samtse, Punakha, W/phodrang, Dagana, and Tsirang.

This book is therefore, a compilation of available information on the species composition and distribution of fish in Western Bhutan. It is published with the aim to provide baseline information for future research as well as for developing management and conservation measures for fisheries. The book is included with quality fish photographs, up to date nomenclature, systematic account and diagnostic characters of the known fish species in the western region. This book differs from other report/publications in Bhutan, in the way that it is more detailed and comprehensive and most important of all, provides information on the distribution of individual fish species with an illustrated map.