This paper reflects the current state of
ichthyofauna in the research made in Bistrita
River Basin, regarding the inventory of the fish
species that inhabit the rivers Calu and Iapa, right
tributaries of the river Bistrita. The data obtained
by us were compared with those existing in the
literature (Bănărescu P., 1964) to capture changes
recorded in the structure of the fish communities
after the human impact appeared during 1960 and
up to present. So, there were made investigations
regarding the composition in the species, the
fisheries of these rivers through the calculation of
the ecological index, and the determination of the
index of biologic integrity (IBI), which reflects
best the actual state of the fish population from
these ecosystems. | 
