Brahmaputra including Barak were the major sources of fishes. Swamps were houses of colourful fishes & exotic varieties. Now environment is highly disturbed with immigrant populations, resulting in silation of rivers beds in addition to d'forestation & erosion.
Now fishes from Myanmar are available at Guwahati. They are big delicious ones, better than Andhra Pradesh fishes.
Strange situation because Assam was a reservoir of fish full of swamps and innumerable rivers.