activities of oil explorations and direct contact of the
crude oil, slugs with water and soil. The unplanned
construction of embankments for preventing floods
causes the loss of habitat, breeding ground and migration
of fish. Several hydroelectric dams have already been
constructed, or are under construction. Unplanned
construction might cause the destruction of habitat,
breeding ground and migration for the rich diversity of
fishes of the north eastern states of India and the
rheophilic fish fauna in particular. The issue of the
development of a fish ladder, which is a major issue in
the construction of dams, has not been seriously